! !NASA Laboratory Astrophysics Workshop 2018
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3456%7!$##*'788999:&5'5:6;<8=%5#>+%86;??5+?8120@84%'',%+/0A/#$%/%56-%/&%B>-5! ! ! Scientific Organizing Committee
Phillip Stancil (UGA), Co-Chair Doug Hudgins (NASA HQ), Co-Chair
Gary Ferland (U. Kentucky) Bill Latter (NASA HQ) Stefanie Milam (NASA GSFC) David Neufeld (Johns Hopkins U.) Ella Sciamma-O’Brien (NASA Ames) Alan Smale (NASA GSFC) Randall Smith (SAO) Artemis Spyrou (Michigan State U.) Lisa Storrie-Lombardi (JPL) Glenn Wahlgren (STScI)
Abstract Book Compiled by Benhui Yang, Yier Wan, Ella Sciamma-O0Brien, and Jeff Deroshia. NASA LAW 2018 Athens, GA April 8-11, 2018
Program (as of April 3, 2018)
Note: All talks will be held in Masters Hall, UGA Center for Continuing Education and Hotel
Sunday April 8 6:30pm - 8:30pm Reception/Registration Pecan Tree Galleria
Monday April 9 Opening Session (Chair: Phillip Stancil) 8:30am - 8:40am Dean Alan Dorsey (UGA) Welcoming remarks
8:40am - 9:10am Doug Hudgins (NASA HQ) Overview of NASA's Laboratory Astrophysics Research Program
9:10am - 9:40am Harshal Gupta (NSF) NSF’s Role in Funding Laboratory Astrophysics
9:40am - 10:00am Coffee break
10:00am - 10:30am Discussion
LAW2018: April 8-11, 2018 1 QS14
10:30am - 11:30am Nancy Brickhouse (SAO) Plenary: An Overview of Laboratory Astrophysics Needs for NASA Missions
11:30am - 12:00pm 1-minute Poster Introductions
12:00pm - 1:00pm Lunch (Banquet Area)
Session 2: X-ray Astronomy (Chair: Alan Smale)
1:00pm - 1:30pm Robert Petre (NASA GSFC) Critical Laboratory Astrophysics Needs for Current and Near- Term NASA X-ray Astrophysics Missions
1:30pm - 2:00pm Frank Timmes (Arizona State U.) Bonanza of Frontiers
2:00pm - 2:30pm Natalie Hell (LLNL) Experimental Laboratory Astro- and Atomic Physics in the X-ray Band
2:30pm - 3:00pm Coffee Break
3:00pm - 3:30pm Panel Discussion
3:30pm - 4:30pm Break-out Sessions: i) FIR/Submm (Room TU) ii) UV/Optical/Mid-IR (Masters Hall) iii) X-ray/EUV (Room VW ) iv) Gamma-ray/Nuclear/Plasmas (Room YZ)
4:30pm - 5:30pm Break-out Session: Databases/codes/archives (Masters Hall)
LAW2018: April 8-11, 2018 2 QS14
5:30pm - 6:30pm Poster Session (Pecan Tree Galleria)
6:30pm Dinner (off-site)
Tuesday April 10 Session 3: Mid-IR to Submm Astronomy (Chair: David Neufeld)
8:30am - 9:00am Kimberly Ennico Smith (NASA SOFIA) SOFIA-enabled Science Lab Astro and Theory Connections
9:00am - 9:30am Els Peeters (U. Western Ontario) Laboratory Needs for IR Observations of PAHs and Dust
9:30am - 10:00am Susanna Widicus-Weaver (Emory U.) Status and Critical Needs for Far-IR Spectroscopy in Laboratory Astrophysics
10:00am - 10:30am Coffee Break
10:30am - 11:00am Panel Discussion
Session 3a: General Contributed Talks
11:00am - 11:15am Frances Cashman (U. South Carolina) Improving Absorption Line Studies of the Interstellar, Circum- galactic, and Intergalactic Medium using Revised Atomic Data
11:15am - 11:30am Debra Richman (Michigan State U.) Nucleosynthesis of 60Fe and Nuclear Physics Constraints
LAW2018: April 8-11, 2018 3 QS14
11:30am - 12:00pm 1-minute Poster Introductions
12:00pm - 1:00pm Lunch (Mahler Hall)
Session 4: UV to Mid-IR Astronomy (Chair: Lisa Storrie-Lombardi)
1:00pm - 1:30pm Klaus Pontoppidan (STScI) Laboratory Needs for JWST and Other NASA Infrared Missions
1:30pm - 2:00pm Steven Federman (U. Toledo) Laboratory Data Needs at UV and IR Wavelengths
2:00pm - 2:30pm Farid Salama (NASA Ames) Laboratory Astrophysics Status and Needs for NASA UV/ Optical/IR Astrophysics Missions
2:30pm - 3:00pm Coffee Break
3:00pm - 3:30pm Panel Discussion
3:30pm - 4:30pm Break-out Sessions: i) FIR/Submm (Room TU) ii) UV/Optical/Mid-IR (Masters Hall) iii) X-ray/EUV (Room VW) iv) Gamma-ray/Nuclear/Plasmas (Room YZ)
4:30pm - 5:30pm Break-out Session: Decadal Survey Planning (Masters Hall)
5:30pm - 6:30pm Poster Session (Pecan Tree Galleria)
LAW2018: April 8-11, 2018 4 QS14
6:30pm Dinner (off-site)
Wednesday April 11
Session 5: Codes and Databases for Astronomy (Chair: Gary Ferland)
8:30am - 9:00am Keith Arnaud (NASA/GSFC) XSPEC
9:00am - 9:30am Adam Foster (CfA) Critical Laboratory Data Needs for NASA Astrophysics Missions
9:30am - 10:00am Peter Bernath (Old Dominion U.) Laboratory Molecular Spectroscopy Data for UV/Optical/IR Astronomy
10:00am - 10:30am Coffee Break
Session 5a: Contributed Talks for Codes and Databases
10:30am - 10:45am Christiaan Boersma (NASA/San Jose State U.) The NASA Ames PAH IR Spectroscopic Database
10:45am - 11:00am Tim Kallman (NASA/GSFC) X-ray Photoionized Models of Emission Spectra
11:00am - 11:15am Marie-Lise Dubernet (Observatory of Paris) Update on VAMDC (Virtual Atomic Molecular Data Centre)
LAW2018: April 8-11, 2018 5 QS14
11:15am - 11:30am Chris Fontes (LANL) A Link between Atomic Physics and Gravitational Wave Spectroscopy
11:30am - 12:00pm Panel Session
12:00pm - 1:00pm Lunch (Mahler Hall)
Session 6: High Density Plasmas (Chair: Artemis Spyrou)
1:00pm - 1:30pm Taisuke Nagayama (Sandia Nat. Lab.) The Z Astrophysical Plasma Properties Collaboration
1:30pm - 2:00pm Laurent Wiesenfeld (U. Grenoble) Contributions of an astrochemical European network to the qualitative understanding of physical astrochemistry: Energy transfers and reaction rates
2:00pm - 2:30pm Final Panel Discussion
2:30pm - 3:00pm Coffee Break
3:00pm - 4:00pm Break-out sessions: i) FIR/Submm (Room V) ii) UV/Optical/Mid-IR (Masters Hall) iii) X-ray/EUV (Room W) iv) Gamma-ray/Nuclear/Plasmas (Room Y) v) Databases, Codes, Archives (Room TU) vi) Decadal Survey Planning (Room Z) 4:00pm -5:00pm Reports from Break-out Sessions: all working groups (Masters Hall)
5:00pm Meeting adjourned
LAW2018: April 8-11, 2018 6 Invited Talks
PAGE Doug Hudgins ? Overview of NASA’s Laboratory Astrophysics Research Program ...... 8 Harshal Gupta ? NSF’s Role in Funding Laboratory Astrophysics ...... 9 Nancy Brickhouse ? An Overview of Laboratory Astrophysics Needs for NASA Missions . . 10 Robert Petre ? Critical Laboratory Astrophysics Needs for Current and Near-Term NASA X-ray Astrophysics Missions ...... 11 Frank Timmes ? A Bonanza of Frontiers ...... 12 Natalie Hell ? Experimental Laboratory Astro- and Atomic Physics in the X-Ray Band . . . . 13 Kimberly Ennico Smith ? SOFIA-Enabled Science Laboratory Astrophysics and Theory Connections ...... 14 Els Peeters ? Laboratory Needs for IR Observations of PAHs and Dust ...... 15 Susanna Widicus Weaver ? Status and Critical Needs for Far-IR Spectroscopy in Laboratory Astrophysics ...... 16 Klaus Pontoppidan ? Laboratory Needs for JWST and Other NASA Infrared Missions . . . . 17 Steven Federman ? Laboratory Data Needs at UV and IR Wavelengths ...... 18 Farid Salama ? Laboratory Astrophysics Status and Needs for NASA UV/Optical/IR Astrophysics Missions ...... 19 Keith Arnaud ? XSPEC ...... 20 Adam Foster ? Critical Laboratory Data Needs for NASA Astrophysics Missions ...... 21 Peter Bernath ? Laboratory Molecular Spectroscopy Data for UV/Optical/IR Astronomy . . 22 Taisuke Nagayama ? The Z Astrophysical Plasma Properties collaboration ...... 23 Laurent Wiesenfeld ? Contributions of an Astrochemical European Network to the Qualitative Understanding of Physical Astrochemistry: Energy Transfers and Reaction Rates 24 Overview of NASA’s Laboratory Astrophysics Research Program Douglas Hudgins NASA Headquarters, Washington, DC
This presentation will provide a current snapshot of the Laboratory Astrophysics research sup- ported under the auspices of NASA’s Astrophysics Research and Analysis (APRA) program. I will summarize the scope and guiding principles of the program, and present demographic information illustrating its current makeup as well as recent trends in such programmatic factors as budget profile and proposal submission/selection statistics. I will also identify some challenges facing the program in the hopes that these issues may stimulate further discussion throughout the workshop.
8 NSF’s Role in Funding Laboratory Astrophysics Harshal Gupta The National Science Foundation, Division of Astronomical Science, Alexandria, VA
The Division of Astronomical Sciences at the National Science Foundation (NSF) supports all areas of astronomy and astrophysics. This includes laboratory astrophysics that seeks to address fundamental scientific questions and critical needs of the wider astronomy community. In addi- tion, NSF’s Divisions of Chemistry and Physics contribute to supporting laboratory astrophysics. This talk will present NSF’s broad portfolio of laboratory astrophysics projects that enable astron- omy, addressing NSF’s role in the broader context of federal funding and emphasizing areas that complement NASA’s priorities.
9 An Overview of Laboratory Astrophysics Needs for NASA Missions Nancy Brickhouse Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
Laboratory astrophysics has contributed to the success of many NASA missions over the last decade. A few examples will demonstrate the effort needed, often requiring synergies among theoretical calculations, experimental tests, and astrophysical data analysis. I will then address specific areas of work needed looking toward the future.
10 Critical Laboratory Astrophysics Needs for Current and Near-Term NASA X-ray Astrophysics Missions Robert Petre NASA Goddard Space Flight Center, Greenbelt, MD
The grating spectrometers on Chandra and XMM-Newton and the X-ray calorimeter on Hitomi have provided the clearest view to date of spectra in the 0.2-10 keV band. These spectrometers have also revealed inconsistencies between observations and calculations, which can best be ad- dressed by laboratory measurements. This talk will review some of the most critical laboratory measurements that will be needed to resolve inconsistencies with and omissions from databases used for comparison with X-ray observations.
11 A Bonanza of Frontiers Frank Timmes Arizona State University, Tempe, AZ
The end states of stars are a rich site of fascinating and intrinsically 3D challenges that include nuclear burning, convection, rotation, radiation transport, magnetic fields, waves, eruptions, and binary partners. This bonanza of physical puzzles is closely linked with compact object formation in core-collapse supernovae and the diversity of observed supernova remnants. Given recent lab- oratory and observational clues that challenge conventional wisdom, the expectation of immense quantities of data from future time domain surveys, and advances in 3D stellar modeling, this talk will seek to spark discussions of nuclear astrophysics laboratory measurements that are needed to advance the science goals of NASA’s current and near-term high energy astrophysics missions.
12 Experimental Laboratory Astro- and Atomic Physics in the X-Ray Band Natalie Hell Lawrence Livermore National Laboratory, Livermore, CA
The X-ray band of 0.1-10 keV shows important characteristic spectral signatures for ions in astrophysically abundant elements between Be and Ni. These provide a suit of plasma diagnostic utilities, covering a wide range of parameter space - provided we sufficiently understand the under- lying atomic physics and the uncertainties of our reference data. We will discuss state-of-the-art experimental facilities and techniques available to measure these atomic physics parameters in controlled laboratory environments. Using examples of existing measurements, we review current capabilities and uncertainties achieved and discuss possible future improvements in accuracy to fulfill the requirements posed by current and future NASA X-ray missions.
13 SOFIA-Enabled Science Laboratory Astrophysics and Theory Connections Kimberly Ennico Smith NASA Ames Research Center, Moffett Field, CA
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a public observing facility, flying above 99% of the Earth’s water vapor, giving access to the infrared (5-600 microns; including Terahertz frequencies) that is unobtainable by ground-based assets. With its suite of modern instruments providing imaging, spectroscopy and polarimetry, SOFIA is used by the international astronomical community to observe a wide range of objects from comets and planets in our solar system to distant galaxies. Laboratory astrophysics has and will continue to play explicit roles in interpreting the spectroscopic data obtained by SOFIA. This talk will focus on existing and upcoming observational assets on SOFIA and sample science cases where tests by lab experiments and theory are invaluable.
14 Laboratory Needs for IR Observations of PAHs and Dust Els Peeters Department of Physics and Astronomy, University of Western Ontario, Canada
The infrared (IR) spectra of galactic and extragalactic objects are dominated by dust contin- uum emission and features arising from dust species, polycyclic aromatic hydrocarbons (PAHs) and fullerenes. Observations with ground-based IR telescopes, the Stratospheric Observatory for Infrared Astronomy (SOFIA), the Infrared Space Observatory, and the Spitzer Space Telescope have made a major step forward in our understanding of molecules and dust in the Universe. In the near future, we live in the era of the James Webb Space Telescope (JWST) which is ideally equipped to address this line of research. Indeed, with its suite of instruments, JWST will revolu- tionize dust and PAH research. In this talk, I will assess the critical laboratory needs essential to interpret future IR astronomical observations in order to fully exploit the investment made.
15 Status and Critical Needs for Far-IR Spectroscopy in Laboratory Astrophysics Susanna Widicus Weaver Department of Chemistry, Emory University, Atlanta, GA
The recent implementation of several new far-infrared observatories, including the Herschel Space Observatory, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the At- acama Large Millimeter/Submillimeter Array (ALMA), has opened our view of the molecular universe and led to rapid advancements in the field of astrochemistry. We can now probe star- and planet-forming regions with unprecedented sensitivity, frequency resolution, and spatial reso- lution. Unfortunately interpretation of many of the observational results is hampered by a lack of supporting laboratory measurements. Historically known as the ”THz-gap”, the Far-IR spectral window has been a challenge for laboratory spectroscopy because of the lack of high-power sources and sensitive detectors, as well as slow data acquisition rates. However, the recent advancements in astronomy in this spectral regime have led to a large push forward in corresponding laboratory spectroscopic capabilities, thanks to both the rapid technology development associated with the observatories, and the flood of astronomical spectral information in need of interpretation. In this talk, I will overview the current state-of-the art in molecular laboratory spectroscopic techniques used to study molecules of astrophysical interest. I will highlight recent successes in laboratory efforts that complement new astronomical observations. I will also discuss the remaining needs for molecular spectroscopic information to support observational astrochemistry.
16 Laboratory Needs for JWST and Other NASA Infrared Missions Klaus Pontoppidan Space Telescope Science Institute (STScI), Baltimore, MD
The James Webb Space Telescope is NASAs premier infrared observatory, with a planned launch in 2020. Covering a wavelength range of 0.6-28 micron, and equipped with a comprehensive set of spectroscopic modes, it will return large amounts of high quality data tracing the molecular universe, from high redshift galaxies, star-forming regions and planet-forming disks, as well as exoplanets and our own solar system. Almost any interpretation of the JWST data set will likely leverage some form of laboratory data, whether it is of gas-phase molecules and atoms, ices, organics or refractory material. While a great deal of laboratory work has already been carried out in support of previous infrared astronomical observatories, there are also many areas where more laboratory work is critical in the next decade. I will review the current landscape and discuss likely laboratory needs for interpreting and understanding JWST data.
17 Laboratory Data Needs at UV and IR Wavelengths Steven Federman Department of physics and Astronomy, University of Toledo, Tolsedo, OH
After describing several recent efforts, I will present ongoing needs for data at UV and IR wavelengths acquired with NASA facilities. The focus will be on atomic and molecular data for chemical modeling and for the determination of elemental abundances in studies of stellar nucleosynthesis. The abundances of key diagnostics rely on accurate oscillator strengths, line positions, and photoabsorption cross sections. Specific examples include oscillator strengths for relative weak lines, photodissociation and photoionization rates for molecular species in interstellar environments, as well as line positions, oscillator strengths, and photoionization rates for n-capture elements.
18 Laboratory Astrophysics Status and Needs for NASA UV/Optical/IR Astrophysics Missions Farid Salama NASA Ames Research Center, Moffett Field, CA
An overview of the status and critical needs in laboratory astrophysics relevant to current and near-term NASA UV/optical/IR astrophysics missions in regards to molecules, PAHs, dust, and ices will be presented.
19 XSPEC Keith Arnaud NASA Goddard Space Flight Center, Greenbelt, MD
XSPEC is the standard software used worldwide for the analysis of high energy astronomical spectra. It has been used in over 9,000 refereed publications over the last 35 years. I will discuss factors that have contributed to its success and issues in long-term maintenance of software on which the field depends.
20 Critical Laboratory Data Needs for NASA Astrophysics Missions Adam Foster Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
The Hitomi satellite revealed very quickly that in the relatively simple energy band from 2-10KeV there are significant discrepancies between modeled spectra both from database to database project and between atomic databases and observed experiment. With future planned missions such as XARM and Athena also putting an emphasis on high resolution spectroscopy, significant improve- ments in spectroscopic databases and emission models will be required to successfully exploit the full potential of these new instruments. Here I will discuss several issues in the current database holdings for the X-ray and EUV wavebands. This includes identifying needs for new atomic data to fill holes, and, crucially, evaluation of the quality and limitations of existing atomic data. Both ex- perimental and theoretical approaches have significant roles to play in this endeavor. Additionally, in the era of high-resolution spectroscopy for all observations, how data is presented to end-user astrophysicists, with limited or no specialist knowledge of atomic or molecular data, will need to be enhanced. New and possibly simplified tools and models are required to enable meaningful use of the results by the community.
21 Laboratory Molecular Spectroscopy Data for UV/Optical/IR Astronomy Peter Bernath Department of Chemistry & Biochemistry, Old Dominion University, Norfolk, VA
Laboratory methods for UV/Optical/IR molecular spectroscopy will be surveyed with a focus on data needs for NASA astrophysics missions. The challenge of data distribution and maintenance of databases such as HITRAN will be discussed.
22 The Z Astrophysical Plasma Properties collaboration Taisuke Nagayama Sandia National Laboratories, Albuquerque, NM
To be provided
23 Contributions of an Astrochemical European Network to the Qualitative Understanding of Physical Astrochemistry: Energy Transfers and Reaction Rates. Laurent Wiesenfeld IPAG, Universit´eGrenoble-Alpes and CNRS, France
In order to comprehend the present chemical state and chemical history of Young Stellar Objects, at the successive stages of their evolution from prestellar core to disks many aspects of chemical physics are needed. In general, chemistry in dilute phases of the gas and grain phases evolution is kinetics dominated, making the quantitative understanding of the chemistry time and space dependent. Retrieving quantitative information from molecular lines of interstellar (and atmospheric) gases more than often requires a precise knowledge of molecular excitation schemes, far from the Local Thermodynamical Equilibrium, of chemical reaction rates, in gas and on surfaces. In order to have a qualitative and quantitative information and critical appraisal of theories and experiments, a European COST network has been set up. We wish to describe some theoret- ical recent advances and workshop reports. This network tries and federates efforts across many European laboratories. It came as the successor of preceding networks and is meant to be the stepping stone of more ambitious efforts to be proposed. We describe the recent advances and shortcomings of reaction rate theory and inelastic scatter- ing theory, with emphasis on the interplay between theory and experiments. By gathering several types of expertise, from applied mathematics to physical chemistry, dialog is made possible, as a step towards new and more adapted theoretical frameworks, capable of meeting the theoretical, methodological and numerical challenges. Interactions with astronomers, observers and modelers are crucial for the mutual understanding of problems, and for the focusing of laboratory efforts.
24 Contributed Talks
PAGE Frances Cashman ? Improving Absorption Line Studies of the Interstellar, Circumgalactic, and Intergalactic Medium using Revised Atomic Data...... 26 Debra Richman ? Nucleosynthesis of Fe60 and Nuclear Physics Constrainta ...... 27 Christiaan Boersma ? The NASA Ames PAH IR Spectroscopic Database...... 28 Tim Kallman ? X-ray Photoionized Models of Emission Spectra ...... 29 Marie-Lise Dubernet ? BASECOL 2018 : A Database for Molecular Collisions ...... 30 Christopher Fontes ? A Link between Atomic Physics and Gravitational Wave Spectroscopy 31 Improving Absorption Line Studies of the Interstellar, Circumgalactic, and Intergalactic Medium using Revised Atomic Data Frances Cashman Department of Physics and Astronomy, University of South Carolina, Columbia, SC
Atomic spectroscopy is used to study the gas in and around galaxies by analysis of the ab- sorption features in the spectra of background quasars. Element abundances derived from the measurement of observed lines in these quasar absorption systems rely strongly on atomic data such as the oscillator strength of electric dipole transitions. We have produced a compilation of recommended oscillator strengths for 576 key transitions for wavelengths longward of 911.753 Angstroms (the H I Lyman limit). This compilation includes results from the NIST atomic spec- tra database and a large number of other studies. In particular, we focus on recent findings from numerous theoretical and experimental physicists for ions of astrophysical interest that have been observed in the interstellar medium (ISM), the circumgalactic medium (CGM), and the intergalac- tic medium (IGM), for selected elements ranging from C to Pb. Differences between the former and the newly recommended values are greater than 25% for approximately 22% of lines with up- dated oscillator strength values. We therefore encourage future ISM, CGM, and IGM absorption line studies to use this compilation. Finally, we note that about 35% of the lines still have >25% or unknown uncertainties, which indicates a strong need to obtain improved atomic data for these lines. Such improvements would benefit a vast range of abundance studies in astrophysics ranging from interstellar clouds to outflows from active galactic nuclei.
26 Nucleosynthesis of 60Fe and Nuclear Physics Constraints Debra Richman National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI
60Fe is created in massive stars prior to core collapse supernova and is one in only a handful of isotopes whose gamma-rays can indicate ongoing nucleosynthesis in the Galaxy. Signature decay lines from its daughter nucleus 60Co can be observed in the Galactic plane using space based gamma-ray instruments. The 2.6 Myr half-life of 60Fe permits gamma-ray observations while still being short enough to be relevant to current Galactic conditions. To interpret these observations a complete understanding of the creation and destruction of 60Fe in the astrophysical environment are required. One of the most critical nuclear properties is the reaction that produces 60Fe, the capture of a neutron on 59Fe. Because 59Fe has a relatively short half-life of 44 days, this experiment is challenging. At the National Superconducting Cyclotron Laboratory (NSCL) a new technique was implemented using a gamma ray calorimeter SuN (Summing NaI detector) in conjunction with unique radioactive isotope beams made at the NSCL and a relatively new analysis technique, the Beta-Oslo method. With these tools, constraints are being made on the nuclear physics parameters used to calculate the neutron capture rate responsible for the production of 60Fe.
27 The NASA Ames PAH IR Spectroscopic Database Christiaan Boersma1,2 1NASA Ames Research Center, Moffett Field, CA 2San Jose State University, San Jose, CA
PAHs are omnipresent across the Universe and play an intrinsic part in the formation and evolution of stars, planets and possibly even life itself. While the PAH infrared (IR) emission fea- tures are now routinely used by astronomers as tracers of star formation and redshift indicators for distant, dust obscured, galaxies, there is a wealth of information in the PAH spectra that remains untapped. To get to this information, there has been a rapid increase in the number of available laboratory and density functional theory (DFT) computed PAH spectra over the past three-plus decades. However, it is only recently that this has lead to the arrival of dedicated public databases. For example, the Italian/French PAH database (astrochemistry.oa-cagliari.inaf.it/database/), the NIST PAH structure index (pah.nist.gov) and the NASA Ames PAH IR Spectroscopic Database (PAHdb; http://www.astrochemistry.org/pahdb), that all aim to provide consistent and high- quality spectroscopic data. It has been the laboratory experiments and quantum chemical calculations carried out at NASA Ames Research Center over the past three-plus decades that have resulted in the un- rivaled collection of PAH spectra that has been assembled into PAHdb. Besides housing this collection, PAHdb also provides online access to the data, powerful on-line and IDL/Python tools (www.github.com/pahdb/) that allow straightforward use of the database and include PAH emis- sion models at different levels of complexity to enable direct comparison with astronomical obser- vations. PAHdb has allowed for a paradigm shift in the way astronomical PAH spectra can be analyzed and interpreted. For example, astronomical PAH spectra can be fitted and analyzed with the PAH spectra in PAHdb, which then allows for the quantitative determination of the state of the PAH population in terms of charge, size, etc. This approach towards PAH spectroscopy provides a new way to probe astrophysical conditions and should prove particularly valuable in the coming JWST-era. This invited talk summarizes the contents of PAHdb’s spectral libraries, the website with its tools and the IDL/Python data analyzes suites. If time allows, the analyses of the spectral map of the Iris Nebula (NGC 7023) obtained by Spitzer will be used to demonstrate how PAHdb can be utilized to interpret vast amounts of data systematically and how insight is gained in the (photo-)evolution of the cosmic distribution of chemical complexity.
28 X-ray Photoionized Models of Emission Spectra Tim Kallman NASA Goddard Space Flight Center, Greenbelt, MD
Chandra and XMM-Newton revealed the presence of partially ionized gas in many sources with compact sources of X-ray continuum, i.e. active galaxies and X-ray binaries, and so are likely photoionized. These spectra have been studied primarily in absorption, and there is a considerable literature utilizing model fits for inferring the properties of the gas. Study of emission from photoionized sources has received less attention, but provides complementary information from some objects. In this talk/poster will review the challenges and advantages of absorption spectra and some of the key results. I will then present examples of photoionization models for emission- dominated sources and discuss the unique modeling challenges associated with these spectra. I will emphasize the challenges they present for our current knowledge of the atomic quantities which are used in model calculations.
29 BASECOL 2018: A Database for Molecular Collisions Marie-Lise Dubernet Observatoire de Paris, France
The poster will present BASECOL 2018 database that is a repository of collisional data and a web service within the Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). It is based on BASECOL 2012 that has been completely restructured: the internal structure, the feeding mecanisms and the user interface. BASECOL contains rate coefficients for the collisional excitation of rotational, ro-vibrational, vibrational, fine and hyperfine levels of molecules by atoms, molecules and electrons, as well as fine structure excitation of some atoms, which are relevant to interstellar and circumstellar astrophysical applications. Additional features are provided such as in- formation on and critical evaluation of the rate coefficient calculations, fitted functions for many available rate coefficients and a section for community information. In addition BASECOL- provides spectroscopic data queried from CDMS, JPL, HITRAN spectroscopic databases using the VAMDC technology. These spectroscopic data are conveniently matched to the in-house collisional excitation rate coefficients using the SPECTCOL sofware package (http://vamdc.eu/software) and the combined sets of data can be downloaded from the BASECOL website (RADEX for- mat). Being a partner of the VAMDC, BASECOL is accessible from the general VAMDC portal (http://portal.vamdc.eu) and from user tools such as SPECTCOL.
30 A Link between Atomic Physics and Gravitational Wave Spectroscopy Christopher Fontes Los Alamos National Laboratory, Los Alamos, NM
Neutron star mergers are promising candidates for the observation of an electromagnetic (EM) signal coincident with gravitational waves. The recent observation of GW170817 [1] appears to be such an event, with gravitational waves confirmed by subsequent EM signals ranging from the infrared to x-ray portions of the spectrum. The properties of the ejecta produced during these events are predicted to play an important role in the electromagnetic transients called macronovae or kilonovae. Characteristics of the ejecta include large velocity gradients and the presence of heavy r-process elements, which pose significant challenges to the accurate calculation of radiative opac- ities and radiation transport. For example, these opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. We use the Los Alamos suite of atomic physics and plasma modeling codes [2] to investigate the use of detailed, fine-structure opacities [3] to model the EM emission from macronovae. Our simulations [4] predict emission in a range of EM bands, depending on issues such as the presence of winds, elemental composition, and viewing angle. This talk emphasizes various atomic-physics aspects of the spectral modeling of neutron star mergers.
References
[1] B.P. Abbott et al, Astrophys. J. Lett. 848, L12 (2017). [2] C.J. Fontes, H.L. Zhang, J. Abdallah, Jr., R.E.H. Clark, D.P. Kilcrease, J. Colgan, R.T. Cun- ningham, P. Hakel, N.H. Magee and M.E. Sherrill, J. Phys. B 48, 144014 (2015). [3] C.J. Fontes, C.L. Fryer, A.L. Hungerford, R.T. Wollaeger, S. Rosswog and E. Berger, preprint, arXiv:1702.02990 (2017). [4] R.T. Wollaeger, O. Korobkin, C.J. Fontes, S.K. Rosswog, W.P. Even, C.L. Fryer, J. Sollerman, A.L. Hungerford, D.R. van Rossum, A.B. Wollaber, preprint, arXiv:1705.07084 (2017).
Acknowledgements
This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396.
31 Posters
Categories:
PAGE 1. Atomic Collisions ...... 32 2. Atomic Spectra ...... 41 3. Astrochemistry ...... 50 4. Dust Properties and Interactions ...... 54 5. Molecular Collisions ...... 58 6. Molecular Spectra ...... 65 7. Interstellar Medium ...... 75 8. Laboratory Facilities ...... 81 9. Nuclear Processes ...... 84 10. Solar and Heliospheric ...... 86 11. Star Formation ...... 88 12. Hydrodynamics ...... 89
Please Note: your poster number is the number in the upper-right corner of your abstract page. 1 1. Atomic Collisions
Symmetric Charge Exchange in Ion-Atom Collisions Steven Bromley Clemson University
Recent observations of r-process elements produced in neutron star mergers motivates exper- imental measurements of multicharged lanthanides. Given that charge exchange is the dominant process in MCI-neutral collisions, we present a gas cell experiment, optimized for measuring energy- and charge-resolved electron capture cross sections. Total electron capture cross sections for beams of 1 − 5 keV Ne, Ar, and Kr ions colliding with noble gases are presented. These results agree well with the model of Rapp and Francis which predicts a decrease in the capture cross section with increasing energy for these symmetric collisions. Future work will investigate asymmetric collisions involving astrophysically relevant ions and targets to aid in constraining cross section estimates for collisions missing in the literature.
32 2 X-ray absorption by interstellar atomic gases near the K-edges of C, O, Ne, Mg, and Si, and the L-edge of Fe Thomas Gorczyca Department of Physics, Western Michigan University
As an ongoing theoretical atomic physics and laboratory astrophysics research program at WMU, we have calculated highly-accurate atomic photoabsorption cross sections using the most robust theoretical methods available. To date, atomic C, O, Ne, Mg, in neutral and ionized forms, have been studied in great detail, combining R-matrix and MCHF analyses with experimental measurements and x-ray observations. Present x-ray absorption studies for atoms consider the heavier, more complicated third-row atomic systems. These include the Si K-edge region (˜1.85 Kev), where the theoretical atomic photoabsorption cross section is needed for a better understand- ing of the observed near-threshold Chandra spectrum (Corrales, et al. 2016). Another important third-row system is atomic Fe, with L-edge photoabsorption peaking near the fine-structure-split 3p(-1) j=3/2 and j=1/2 thresholds at ∼710 eV and ∼720 eV. Computing reliable R-matrix data for this region therefore requires a relativistic treatment beyond our previous calculations for s- vacancy systems. The latest results for Si and Fe will be shown, and photoabsorption in the ISM by molecular and solid-state sytems will also be discussed.
33 3 Electron Impact Ionization of C+ from Ground and Excited States Stuart Loch Department of Physics, Auburn University
The R-matrix with pseudostates method is used to calculate the electron impact ionization of C+, with the results being compared with literature values where possible. The cross sections and rate coefficients are resolved by both initial and final state, allowing metastables to be tracked in the ionization balance. The possible impact of the new ionization data on modeling results is also explored.
34 4 Electron-Impact K-Shell Ionization of Te, Ta, and Bi Michael S. Pindzola Department of Physics, Auburn University
Electron-impact K-shell ionization cross sections for Te, Ta, and Bi are calculated using a fully- relativistic distorted-wave method. One set of calculations only include the two-body electrostatic interaction, while the other set includes the full two-body retarded electromagnetic interaction. The theoretical cross sections are compared with recent measurements made at the Institute for Physics at the University of Sao Paulo, Brazil. Similar calculations may be made for many heavy atoms of astrophysical interest.
35 5 Electron-Impact Single and Double Ionization of W+ Michael S. Pindzola Department of Physics, Auburn University
Electron-impact single and double ionization cross sections for W+ are calculated using a semi-relativistic distorted-wave method. The single ionization cross sections include contributions from the direct ionization of the 6s and 5d subshells as well as excitation-autoionization contribu- tions from the 4f → nl, 5p → nl, and 5s → nl transitions. The double ionization cross sections include contributions from the direct ionization of the 4f and 5p subshells as well as excitation- autoionization contributions from the 5p → nl and 5s → nl transitions. Similar calculations may be made for many heavy atoms and ions of astrophysical interest.
36 6 Laboratory data compellingly support a charge-exchange mechanism for the ’Dark matter’ ∼3.5 keV X-ray line Chintan Shah Max-Planck-Institut f¨urKernphysik Heidelberg, Germany
Recent X-ray observations of a mysterious signal at ∼3.5 keV from nearby galaxies and galaxy clusters have sparked tremendous interest in the scientific community and have given rise to a tide of publications attempting to explain the origin of this signal [1]. It has been hypothesized that the line is the result of decaying sterile neutrinos a potential dark matter particle candi- date presumably based on the fact that this X-ray line is not available in the standard spectral databases and models for thermal plasmas. Cautiously, Gu et al. [2] have pointed out an alter- native explanation for this phenomenon: charge exchange between bare ions of sulfur and atomic hydrogen. Their model shows that X-rays should be emitted at 3.5 keV by a set of S XVI transi- tions from high Rydberg states to the ground state. In the laboratory, we tested this hypothesis by measuring K-shell X-ray spectra of highly ionized sulfur ions following charge exchange with gaseous molecules in an electron beam ion trap. We produced bare S XVII and H-like S XVI ions and let them capture electrons in collisions with molecules while recording X-ray spectra. A clear signal at 3.5 keV shows up in the charge-exchange induced spectrum under a broad range of experimental conditions. The inferred X-ray energy of 3.47 0.06 keV is in full accord with both the astrophysical observations and theoretical calculations and confirms the novel scenario proposed by Gu [2]. Taking the experimental uncertainties and inaccuracies of the astrophysical measurements into account, we conclude that the charge exchange between bare sulfur and hydrogen atoms can outstandingly explain the mysterious signal at around 3.5 keV [3]. References
[1] E. Bulbul et al., Astrophys. J. 13, 789 (2014) [2] L. Gu et al., A & A L11, 584 (2015) [3] C. Shah et al., Astrophys. J. 833, 52 (2016)
37 7 Polarization of K-shell Dielectronic Recombination Satellite Lines of Fe XIXXXV Chintan Shah Max-Planck-Institut f¨urKernphysik Heidelberg, Germany
For a wide range of temperatures, resonantly captured electrons with energies below the exci- tation threshold are the strongest source of X-ray line formation in hot plasmas containing highly charged Fe ions. The angular distribution and polarization of X-rays emitted due to these processes were experimentally studied using an electron beam ion trap. The electron-ion collision energy was scanned over the K-shell dielectronic, trielectronic, and quadruelectronic recombination resonances of Fe XIXXXV with an exemplary resolution of ∼6 eV. The angular distribution of induced X-ray fluorescence was measured along and perpendicular to the electron beam propagation direction [1, 2]. Subsequently, the polarization of X-ray fluorescence was also measured using a novel Compton polarimeter [3, 4]. The experimental data reveal the alignment of the populated excited states and exhibit a high sensitivity to the relativistic effects [3, 5]. We observed that most of the transitions lead to polarization, including hitherto-neglected trielectronic and quadruelectronic recombination channels. These channels were found to dominate the polarization of the prominent Fe K-alpha X-ray line emitted by hot anisotropic plasmas in a wide temperature range. The present experi- mental results comprehensively benchmark full-order atomic calculations carried out with the FAC code [6]. We conclude that accurate polarization diagnostics of hot anisotropic plasmas produced by solar flares and laboratory fusion devices can only be obtained under the premise of careful inclusion of relativistic effects and higher-order recombination channels which were often neglected in previous works [1, 2]. Furthermore, we also demonstrate the suitability of the applied tech- niques and experimental data for accurate directional diagnostics of the electron or ion beams in hot plasmas [1].
References
[1] C. Shah et al., Astrophys. J. Suppl., 234, 27 (2018) [2] C. Shah et al., Phys. Rev. E 93, 061201 (R) (2016) [3] C. Shah et al., Phys. Rev. A 92, 042702 (2015) [4] S. Weber et al., Rev. Sci. Instr. 86, 093110 (2015) [5] P. Amaro and C. Shah et al., Phys. Rev. A 95, 022712 (2017) [6] M. F. Gu, Can. Phys. J 86, 675 (2008)
38 8 The Contribution of Double Electron Capture Processes to Charge Exchange with Multielectron Targets Jason P. Terry1, P. C. Stancil1, R. S. Cumbee2, Patrick D. Mullen3 1 Department of Physics and Astronomy, University of Georgia 2 NASA Goddard Space Flight Center 3 Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana
Corresponding author email: [email protected]
Previous investigations into charge exchange and its applications to X-ray spectroscopy have tended to focus almost exclusively on single electron capture processes. Mounting evidence suggests that neglecting the contribution of double electron capture may yield inaccurate results. Accordingly, charge exchange cross sections for single and double electron capture are calculated using multi- channel Landau-Zener theory for the system Ne10+ +He. Doubly-excited (n,l,n’,l’)-resolved double electron capture cross sections are generated then used in conjunction with branching ratios to determine cross sections for radiative stabilization through true double capture and autoionization. These cross sections are used to generate X-ray spectra for each of the processes. Results indicate that the inclusion of double electron capture processes is necessary if one is to properly describe the resulting spectral shape.
39 9 Fine-Structure Excitation of Fe II and Fe III due to Collisions with Electrons Yier Wan1, Yueying Qi1,4, C. Favreau2, S. Loch2, P. C. Stancil1, C.P Ballance3, and B. M. McLaughlin3 1Department of Physics and Astronomy, University of Georgia 2 Department of Physics, Auburn University 3 Queen’s University Belfast 4 Jiaxing University, China
Corresponding author email: [email protected]
Atomic data of iron peak elements are of great importance in astronomical observations. Among all the ionization stages of iron, Fe II and Fe III are of particular importance because of the high cosmic abundance, relatively low ionization potential and complex open d-shell atomic structure. Fe II and Fe III emission are observed from nearly all classes of astronomical objects over a wide spectral range from the infrared to the ultraviolet. To meaningfully interpret these spectra, as- tronomers have to employ highly complex modeling codes with reliable collision data to simulate the astrophysical observations. The major aim of this work is to provide reliable atomic data for di- agnostics. We present new collision strengths and effective collisions for electron impact excitation of Fe II and Fe III for the forbidden transitions among the fine-structure levels of the ground terms. A very fine energy mesh is used for the collision strengths and the effective collision strengths are calculated over a wide range of electron temperatures of astrophysical importance (10-2000 K). The configuration interaction state wave functions are generated with a scaled Thomas-Fermi-Dirac- Amaldi (TFDA) potential, while the R-matrix plus intermediate coupling frame transformation (ICFT), Breit-Pauli R-matrix and Dirac R-matrix packages are used to obtain collision strengths. Influences of the different methods and configuration expansions on the collisional data are dis- cussed. Comparison is made with earlier theoretical work and differences are found to occur at the low temperatures considered here.
40 10 2. Atomic Spectra
The Laboratory Astrophysics Program at Imperial College London Maria Teresa Belmonte Imperial College London
Accurate oscillator strengths (transition probabilities, log(gf)) and wavelengths are indispens- able to analyse stellar spectra and obtain chemical abundances, as well as other stellar parameters. However, the quantity and quality of the existing data lies far from the current needs of the as- tronomers, remaining the Achilles’ heel of Galactic archaeology. This situation has resulted in an acute need for laboratory measurements of matching accuracy and completeness to use the full potential of the very expensively acquired astrophysical spectra. This can be addressed by using high-resolution Fourier Transform Spectroscopy (FTS), which has evolved dramatically over the past thirty years and nowadays, it is able to provide very accurate transition probabilities, energy levels and wavelengths for many spectral lines needed by astrophysicists. The Fourier Transform spectrometer at Imperial College London works in the VUV-Visible region with a resolution of 2 000 000 at 200 nm. We can acquire spectra of neutral, singly and doubly ionized species by using hollow cathode and Penning discharge lamps. We collaborate with the National Institute of Standards and Technology (NIST) and the University of Lund to extend our measurements into the infrared region. The aim of this poster is to explain the current capabilities of our experiment in a comprehensive way to bring the astronomy community closer to the field of laboratory astrophysics. We want to launch an appeal to collaborate with all those astronomers who need accurate atomic data and encourage further dialogue between our laboratory and scientists who need accurate oscillator strengths and wavelengths. This exchange of ideas will help us to focus our efforts on the most urgently needed data.
41 11 Astrophysical Applications for Charge-Exchange Collisions with H, He, and H2 Targets Renata Cumbee1, P. Mullen2, D. Lyons3, M. Fogle4, D. R. Schultz5, R. L. Shelton3, and P. C. Stancil3 1 NASA Goddard Space Flight Center 2 Department of Astronomy, University of Illinois at Urbana-Champaign 3 Department of Physics and Astronomy, University of Georgia 4 Department of Physics, Auburn University 5 Northern Arizona University
Corresponding author email: [email protected]
When a hot plasma collides with a cold neutral gas, interactions occur between the constituents at the interface of the collision, including charge exchange (CX). CX is a process in which an electron can be transferred from a neutral atom or molecule into an excited energy level of an ion. Following this transfer, the excited electron relaxes to lower energy levels, emitting X-rays. This process has been established as a primary source of X-ray emission within our solar system, such as when the solar wind interacts with cometary and planetary atmospheres, and outside of our solar system, such as in the hot outflows of starburst galaxies. As the CX X-ray emission spectrum varies greatly with collision velocity, it is critical that realistic CX data are included in X-ray spectral models in regions in which CX might be significant so that the ion abundance and plasma velocities can be estimated most accurately. Here, a set of X-ray line ratios and CX spectra will be shown for a variety of collision velocities for C-Cl ions colliding with H, He, and H2. An X-ray emission model performed in XSPEC that includes these line ratios will then be presented for a region of the Cygnus Loop supernova remnant and the starburst galaxy M82 in order to highlight the variation in CX spectral models with collision energy and neutral target species.
42 12 High Resolution Photoelectron Imaging of − − Carbon Phosphide Anions: CP and C2P Joseph Czekner Department of Chemistry, Brown University
joseph [email protected]
Photoelectron and photodetachment spectroscopies are powerful tools to probe the electronic and vibrational structure of negatively-charged ions and neutral molecules. We have recently developed a high-resolution photoelectron imaging apparatus that allows vibrational structure of neutral molecules to be resolved down to several cm−1. Electronic and spectroscopic information about the anions can be obtained from hot band transitions or electronic excited states of the anions (either valence excited states or dipole-bound excited states) via photodetachment spectroscopy. Here we present our recent results for two carbon phosphide anions. We have measured the electron − affinities of CP and C2P for the first time, in addition to the vibrational frequencies of the CP and − C2P anions. Our study confirmed previous measurements of the neutral vibrational frequencies and was used to benchmark high level theoretical calculations. Very recently, the addition of a − tunable laser source has allowed us to discover a dipole bound state of C2P for the first time. We have found that the neutral core in C2P has two spin-orbit states, which both possess a dipole bound state. Resonant photoelectron spectra show that vibrational autodetachment from the dipole-bound states is state-selective to a specific spin-orbit state. We have found direct spectroscopic evidence that the spin of the dipole-bound electron does not couple with the neutral core. Since neutral C2P has been found in the interstellar medium (ISM), The observation of the − dipole-bound state for C2P provides a mechanism for its formation in the ISM.
43 13 X-ray Spectroscopy of Highly Charged Ions Amy Gall Department of Physics and Astronomy, Clemson University
Highly charged ions (HCIs) are found throughout the universe in sources such as comets, stars, galaxy clusters, and supernovae remnants. Spectra produced by HCIs provide important plasma diagnostics including plasma temperature, density, and ionization state. With the advent of the Electron Beam Ion Trap (EBIT), we are able to create and trap HCIs in the lab and produce a wide range of atomic and collisional data to support areas such as X-ray astrophysics and the fusion device community. The quasi-monoenergetic nature of the electron beam allows for a degree of charge state selectivity and for the systematic study of plasma dynamics and atomic structure. Here we provide an overview of the NIST EBIT facility and present astrophysically relevant X- ray spectroscopic results. We also give an update on the current status of the refrigerated EBIT (R-EBIT) planned to come online soon at the Smithsonian Astrophysical Observatory.
44 14 Ultraviolet Transitions of Singly Ionized Lead, Tin and Germanium Negar Heidarian Department of Physics and Astronomy, The University of Toledo
Radiative transitions, especially the ultraviolet absorption lines of heavy elements, are of great importance in astrophysics. They help us understand neutron capture processes responsible for production of heavy elements during stellar evolution. Abundances in the interstellar medium (ISM) provide a snapshot of their production in the current epoch. Knowledge of interstellar abundances for these elements requires oscillator strengths (f-values) to convert the amount of ab- sorption into abundances. We present the results of our homologous studies on the UV transitions involving ns2nd 2D and nsnp2 2D terms to the ground term for the elements from group IV of the periodic table, namely Pb II, Sn II and Ge II. Transition rates and the corresponding f-values measured with beam-foil techniques at the University of Toledo Heavy Ion Accelerator will be reported and compared with the most recent theoretical efforts including ours. The impact of the newly determined f-values on gas phase abundances in the ISM will be discussed.
45 15 High precision calibration of interstellar oxygen absorption Maurice Leutenegger NASA Goddard Space Flight Cente
Several articles over the last 17 years have noted a large discrepancy between the laboratory rest wavelength of the strong neutral atomic O I 1s-2p transition and the wavelengths measured in numerous Chandra and XMM grating spectra of neutral gas absorption backlit by bright X-ray binaries. If interpreted as an astrophysical Doppler shift, it would lead to the dubious conclusion that Galactic neutral gas along many lines of sight is receding from us at velocities of order 300 km/s. Spurred by this jarring conundrum, we have made improved high-precision measurements of the transition energies of molecular O2 that were used to calibrate the neutral O I lines. We calibrated a synchrotron beamline, featuring a high resolution plane grating monochroma- tor, using a portable electron beam ion trap (EBIT). The EBIT was used to produce He-like ions of nitrogen and oxygen, with fluorescence of the 1s-np transitions recorded in large area solid-state detectors. Simultaneously with this, we recorded the photoion yield in an O2 gas cell. With this experiment we calibrated the O2 Rydberg spectrum to a precision of 30 meV using the 1s-6p and 1s-7p transitions of He-like N VI as standards, which can be calculated with sub-ppm accuracy. We find a disagreement of ∼500 meV with previously published measurements. Our new calibration standard reduces the line-of-sight averaged velocity of Galactic neutral O I to be consistent with zero, as expected.
46 16 Measurements of Atomic Data at NIST for Space Astronomy Gillian Nave National Institute of Standards and Technology
For many decades, the Atomic Spectroscopy Group at NIST has measured atomic data of vital use to astronomy and other fields using high resolution spectrometers that are found in few other places in the world. These include a 2-m path difference Fourier transform (FT) spectrometer, a vacuum ultraviolet FT spectrometer, a 10.7-m normal incidence spectrograph and a 10-m grazing incidence spectrograph. We are collaborating with groups at Imperial College London, UK and the University of Wisconsin-Madison, WI to measure wavelengths, energy levels, oscillator strengths, and hyperfine structure constants that are needed for the analysis of stellar spectra from space- based and ground-based astronomical spectrographs. Recent work has focused around large scale analyses of neutral and singly-ionized iron-group elements in collaboration with Imperial College London, and the measurement of atomic oscillator strengths in collaboration with the University of Wisconsin-Madison. We shall present current work on large-scale analyses of Sc II and Mn II, hyperfine structure in Co II, and atomic oscillator strengths in Sc II.
47 17 NIST Atomic Databases and Tools Yuri Ralchenko The National Institute of Standards and Technology
We will present the recent developments of the NIST atomic databases and tools. Several new versions of the Atomic Spectra Database were released over the last six months with expanded data coverage and new added features, e.g., output of atomic data uncertainties. A new database for laser-induced breakdown spectroscopy (LIBS) has been developed. We will also present our online calculational tools for plasma population kinetics and emission calculations.
48 18 Lifetime Measurements of Ca using Laser Induced Fluorescence Alex Scherer Department of physics, University of Wisconsin-Madison
We measure the radiative lifetimes of 21 neutral and 2 singly ionized calcium energy levels between 23,652.30 and 48,562.52 cm−1 using time resolved laser induced fluorescence with uncer- tainties of ∼ ± 5%. These lifetimes are compared against previous experimental measurements[1][2] and more recent theoretical calculations[3]. Calcium is an alpha-element and its transitions are used in astrophysical contexts to measure [α/Fe] of stellar sources. These measurements can give insight into the chemical evolution of galaxies because different [α/Fe] are produced by differ- ent types of supernovae. Highly accurate Ca transition probabilities are needed to detect small changes in [α/Fe], and these radiative lifetimes will be combined with emission branching fractions measured using high resolution spectroscopy to produce accurate transition probabilities.
References
[1] M. Aldenius, H. Lundberg, and R. Blackwell-Whitehead, Astronomy & Astrophysics 502, 989 (2009). [2] G. Jonsson, C. Levinson, S. Svanberg, Phys. Scr. 30 (1984) 65. [3] Y. Yu and A. Derevianko, Atomic Data and Nuclear Data Tables 119, 263 (2018).
49 19 3. Astrochemistry
Radiative Association of Carbon and Atomic Hydrogen James Babb1, B. M. McLaughlin2 1Smithsonian Astrophysical Observatory 2Queen’s University Belfast
Corresponding author email: [email protected]
The rate coefficients for the formation of CH by the radiative association of C and H are sensitive to a potential energy barrier of uncertain magnitude in the B state of CH. We remove the uncertainty with new ab initio calculations and recently compiled and evaluated molecular data and we calculate the cross sections and rate coefficients for the radiative association process.
50 20 Gas-Phase Exploration of PAHs and Cosmic Carbon by Laboratory Methods Paul Dunk National High Magnetic Field Laboratory, Florida State University
At the National High Magnetic Field Laboratory at Florida State University, we study ener- getic reactions and formation processes of PAHs, as well as related forms of cosmic carbon, at the molecular level by laser-based methods, analyzed by state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry. Further, we aim to explore the integration of additional laboratory setups and spectroscopic capabilities of interest to NASA-sponsored user communities.
51 21 An Argon-Oxygen Covalent Bond in the ArOH+ Molecular Ion Philipp Wagner Department of Chemistry, University of Georgia
Although the OH+ cation is decidedly a triplet (3) being over 50 kcal mol−1 more stable than the corresponding singlet (1∆), binding to an argon atom can reverse this situation. The noble gas forms a strong donor-acceptor bond to the excited state singlet cation with a bond strength of 66.4 kcal mol−1 at the CCSDT(Q)/CBS level of theory. This makes the singlet 3.9 kcal mol−1 more stable than the most favorable triplet Ar-HO+ complex. In a cold molecular beam experiment we have prepared both, singlet and triplet, isomers of this molecular ion depending on the employed ion source. Photodissociation spectroscopy in combination with messenger atom tagging reveals that the two observed spin isomers exhibit completely different spectral signatures in the infrared and the O-H stretching fundamentals differ by about 900 cm−1. These findings might encourage the search for a new potential interstellar noble gas molecule.
52 22 Revisiting NLTE Rovibrational Excitation of CO in UV Irradiated Environments Ziwei Zhang1, Benhui Yang1, K. M. Walker2, R. C. Forrey3, N. Balakrishnan4, and P. C. Stancil1 1 Department of Physics and Astronomy, University of Georgia 2 Notre Dame College 3 Penn State University, Berks Campus 4 University of Nevada, Las Vegas
Corresponding author email: [email protected]
Being the second most abundant molecule in the ISM, CO has been well observed and studied as a tracer for many astrophysical processes. Highly rovibrationally excited CO emission is used to reveal features in intense UV-irradiated regions such as the inner rim of protoplanetary disks, carbon star envelopes, and star forming regions. Collisional rate coefficients are crucial for non- local thermodynamic equilibrium (NLTE) molecular analysis in such regions, while data for high rovibrational levels for CO were previously unavailable. Here we revisit CO excitation properties with comprehensive collisional data including high rovibrational states (up to v=5 and J=40) col- liding with H2, H and He, in various NLTE astrophysical environments with the spectral modeling packages RADEX and Cloudy. We studied line ratio diagnostics between low- and high-vibrational transitions with RADEX. Using Cloudy, we investigated molecular properties in complex environ- ments, such as photodissociation regions and the outflow of the carbon star IRC+10216, illustrating the potential for utilizing high rovibrational NLTE analysis in future astrophysical modeling.
Acknowledgements
This work was supported by NASA Grants NNX15AI61G and NNX16AF09G.
53 23 4. Dust Properties and Interactions
High Energy Processing of Polycyclic Aromatic Hydrocarbons: Implications for the PAH Emission Bands Andrew Mattioda NASA Ames Research Center
Carbon-rich interstellar dust, composed of Polycyclic Aromatic Hydrocarbons (PAHs) is com- mon and abundant throughout the Universe. It is a key component of virtually all phases of our Galaxys interstellar medium (ISM). Observations from telescopes such as the Spitzer Space Telescope reveal that this dust also dominates the mid-infrared (MIR) emission from many other galaxies. This dust is traced by its characteristic MIR emission spectrum with prominent bands at 3.3 (3030), 6.2 (1613), 7.7 (1300), and 11.2 (893) µm (cm−1). However these bands display variations in band positions and band profiles. These emission bands also exhibit a variable un- derlying continuum typically extending between 6 and 9 µm (1670 and 1111 cm−1). We recently concluded preliminary experiments regarding the processing of solid state PAH thin films via high energy protons and electrons, as well as UV photons. As identified by infrared spectroscopy, these experiments produced some very interesting results with potential implications for the PAH emis- sion bands. This presentation will discuss the impact of proton, electron, and UV irradiation have on PAHs and the potential implications on the PAH bands.
54 24 Production and Characterization of Cosmic Grains Analogs with the NASA Ames’ COSmIC Facility Ella Sciamma-O’Brien1,2, Cesar Contreras2, Lisseth Gavilan1, and Farid Salama1 1NASA Ames Research Center, Moffett Field, CA 2 Bay Area Environmental Research Institute, Moffett Field, CA
Corresponding author email: [email protected]
Complex carbon molecules and ions (hydrocarbons, PAHs, fullerenes) are ubiquitous in space and form the building blocks of the carbonaceous components of cosmic dust grains, ultimately contributing to the formation of planets. The COsmic SImulation Chamber (COSmIC) is a unique facility developed at NASA Ames to generate, monitor, and analyze gas phase hydrocarbons and PAHs, as well as solid carbon grain particles in the laboratory, under controlled conditions representative of interstellar and circumstellar environments[1]. Using this experimental facility, it is possible to investigate the carbon life cycle from the formation of small neutral and ionized hydrocarbons and PAHs in the gas phase, to solid carbon grains. This is achieved by using a pulsed slit discharge nozzle (PDN) to (1) produce an adiabatic jet expansion and cool down Ar- hydrocarbon gas mixtures to astrophysically-relevant temperature (50-150 K) before (2) inducing chemistry by generating a plasma discharge in the stream of the expansion. This plasma-induced chemistry results in the formation of more complex molecules and solid particles, analogs of cosmic grains. Both the gas and solid phases can be characterized (see Salama et al. and Bejaoui et al.’s contributions in this volume). The cosmic grain analogs are produced in situ in the plasma expansion (i.e., without wall effects), carried by the accelerated gas in the expansion, and can then be deposited on different substrates placed 5 cm downstream of the electrodes, for further ex situ analysis[2]. Here, we present the results of a preliminary solid phase ex-situ analysis of cosmic grain analogs produced at low temperature in COSmIC from two different gas mixtures: Ar/CH4 (95:5) and Ar/C2H2 (95:5). Scanning Electron Microscopy (SEM) imaging was used to provide insight on the morphology and growth structure of the grains produced in COSmIC, and to investigate how the precursors used to produce the grains affect these parameters. This SEM study has shown that heavier precursors in the initial mixture produce larger grains and in larger quantity, as a result of a more complex chemistry: the Ar-CH4 grains range from 10 to 80 nm in diameter with a 2 density of 2.1 grains/m , while the Ar-C2H2 grains range from 60 to 500 nm with a density of 3.5 grains/m2. A change in the morphology was also observed, where grains produced from acetylene
(C2H2) precursors were more spherical than grains produced from methane (CH4). Future work includes using heavier hydrocarbons and PAHs as precursors to produce cosmic grain analogs, and analyzing these grains with SEM as well as characterizing their NIR to FIR optical properties to provide critical information (morphology, optical constants) to the broad scientific community, for use in radiative transfer models in particular, and to help decipher and enhance the return data from space observations.
55 References
[1] Salama, F., Sciamma-O’Brien E., Contreras C., Bejaoui S. in IAU Proceedings Series (2018), in press. [2] NASA Press RELEASE 14-129: NASA Simulator Successfully Recreates Space Dust, htps://www.nasa.gov/press/2014/may/nasa-simulator-successfully-recreates-space-dust/
Acknowledgements
This research is supported by the APRA Program of NASA SMD. The authors acknowledge the technical support of E. Quigley. L.G. acknowledges the support of the NPP Fellowship program.
56 25 Synthesis and Characterization of Large PAH samples via Laser Photochemical Polymerization Ian Webster Department of Chemistry, University of Georgia
Through laser desorption time-of-flight mass spectroscopy (LD:TOF:MS) experiments on com- mercially available polyaromatic hydrocarbons (PAHs), an unexpected mass peak at nearly twice the monomer mass has been detected. Pressed pellets of perylene have been shown to have a large peak at m/z 252 for the monomer, but also a second peak at m/z 500 for the dimerized PAH with the loss of four hydrogens, when struck with a Nd:YAG laser frequency tripled to 355 nm. Similar measurements have also been found for other PAH pellet samples, including coronene and pyrene. Characteristic loss of hydrogen indicates these samples are forming polymer chains rather than being held via van der Waals interactions between the PAH monomers. Current research is ongoing into forming physical samples of the polymerized dimer via laser desorption of a PAH pressed pellet with a KrF excimer laser under vacuum (1E-3 Torr). The spray from the laser desorbed pellet is collected onto a quartz slide for study via UV-visible spectroscopy. Solid-sample material is collected from quartz slide for further study via infrared spectroscopy and LD:TOF:MS for comparison with previous results. Ongoing research is being performed to try and purify the sample via methods such as differential sublimation.
57 26 5. Molecular Collisions
Mixed Quantum/Classical Theory for Description of Molecular Collisions in Astrophysical Environments Dmitri Babikov Department of Chemistry, Marquette University
A mixed quantum/classical theory (MQCT) is developed to describe inelastic scattering of molecules in a broad range of collision energies. In this simplified approach the translational motion of collision partners is treated classically, while the internal degrees of freedom -rotational and/or vibrational motion - are treated quantum mechanically. Calculations of rotationally inelastic cross sections were carried out within this framework, and results were compared against the exact full quantum calculations for several real systems, starting with the simplest diatomic + atom collisions, such as H2+He, and going up to such complicated examples as rotational excitation of methyl formate HCOOCH3+He (astrophysically important small organic molecule), or the fundamentally important case of collision between two general asymmetric-top rotor molecules such H2O + H2O (important in cometary comas). The mixed quantum/classical method remains affordable and reasonably accurate, in particular at high collision energies, where it can probably replace the standard full-quantum approach.
58 27
+ Laboratory Measurements for H3 Deuteration Reactions Kyle Bowen Department of Astronomy, Columbia University
Deuterated molecules are important chemical tracers of protostellar cores. At the ∼106 cm−3 particle densities and ∼20 K temperatures typical for protostellar cores, most molecules freeze + onto dust grains. A notable exception is H3 and its isotopologues. These become important carriers of positive charge in the gas, can couple to any ambient magnetic field, and can thereby + alter the cloud dynamics. Knowing the total abundance of H3 and its isotopologues is important + + for studying the evolution of protostellar cores. However, H3 and D3 have no dipole moment. They lack a pure rotational spectrum and are not observable at protostellar core temperatures. + + Fortunately H2D and D2H have dipole moments and a pure rotational spectrum that can be excited in protostellar cores. Observations of these two molecules, such as with the Stratospheric Observatory for Infrared Astronomy (SOFIA), combined with astrochemical models, provide in- + formation about the total abundance of H3 and all its isotopologues. The inferred abundances, + though, rely on accurate astrochemical data for the deuteration of H3 and its isotopologues. Here we present laboratory measurements of the rate coefficients for three important deuterating re- + + + + + + actions, namely D + H3 /2D /D2H → H + H2D /D2H /D3 . Astrochemical models currently rely on rate coefficients from classical (Langevin) or semi-classical methods for these reactions, as fully quantum-mechanical calculations are beyond current computational capabilities. Laboratory studies are the most tractable means of providing the needed data. For our studies we used our novel dual-source, merged fast-beams apparatus, which enables us to study reactions of neutral atoms and molecular ions. Co-propagating beams allows us to measure merged-beams rate coeffi- cients as a function of collision energy. We extract cross section data from these results, which we then convolve with a Maxwell-Boltzmann distribution to generate thermal rate coefficients. Here we present our results for these three reactions and discuss some implications.
59 28 Fine-Structure-Resolution for Rovibrational Excitation of CN due to H2 Nat Byrd, Benhui Yang, P. C. Stancil Department of physics and Astronomy, University of Georgia
Corresponding author email: [email protected]
Diatomic molecules can be readily excited in interstellar environments exposed to intense UV radiation, such as the inner rim of a protoplanetary disk. Non-thermal populations of excited rovibrational levels can result, for example, following decay from electronically excited states to the electronic ground state. Competition between radiative decay and collisional processes, mostly due to H2, determine the resulting rovibrational emission spectrum. For CN, and other open-shell molecules, the resulting spectrum will be complicated due to fine-structure splitting of the rota- tional levels. In some cases, fine-structure resolution has been previously computed for rotational transitions in atom- or diatom-diatom collisional processes. Here we present the first fine-structure resolution for vibrational deexcitation for CN colliding with H2. The collisional cross sections were computed using a 6D potential energy surface with a full close-coupling approach. Fine-structure resolution is obtained by adopting an angular momentum recoupling scheme to transform the scattering matrices to a recoupled basis. Here we present low-energy calculations for the v=1 to 0 transition.
Acknowledgements
This work was supported by NASA Grant NNX16AF09G.
60 29 Dissociative Recombination Measurements on Hydride Molecular Ions for Astrochemistry Daniel Wolf Savin Columbia Astrophysics Laboratory, Columbia University
Dissociative recombination (DR) of electrons with molecular cations is a key chemical process in the cold interstellar medium (ISM). DR affects the composition, charge state, and energy balance of molecular clouds in the ISM. Astrochemical models for clouds in the ISM require reliable total DR cross sections as well as knowledge of the chemical composition of the neutral DR products. We are carrying out a series of DR measurements for astrophysically relevant molecular ions using a merged electron-ion beams technique. Past work was performed utilizing the recently decommissioned TSR heavy-ion storage ring located at the Max-Planck-Institute for Nuclear Physics (MPIK) in Heidelberg, Germany. The limitation of the room temperature TSR is that the ions have internal temperatures of 300 K or greater, warmer than the typical ∼10-100 K temperatures of the cold ISM. To address this issue, we have implemented and are now operating a merged electron-beam setup at the heavy ion Cryogenic Storage Ring (CSR) at MPIK. CSR has an internal temperature of ∼10 K. The low temperatures in CSR enable stored molecular cations with a dipole moment to come into equilibrium with the blackbody radiation of the CSR chamber, establishing an excitation level similar to that expected in the cold ISM. Here we report on our TSR results and recent progress detector development relevant to future DR studies on CSR. This work is supported, in part, by NASA, NSF, MPIK and DFG.
61 30 Computational Investigations of Rovibrational Quenching of HD due to Collisions in the Interstellar Medium Clark G. Veazey, Benhui Yang, Yier Wan, P. C. Stancil Department of Physics and Astronomy, University of Georgia
Corresponding author email: [email protected]
When conducting an examination of distant astronomical objects, scientists rely on measurements derived from astronomical observations of these objects, which are primarily collected using spec- troscopy. In order to interpret spectroscopic data collected on astronomical objects, it is necessary to have a background of accurate dynamical information on the behavior of stellar molecules at ones disposal. Seeing as most of the observable infrared radiation in the universe is emitted by molecules excited by collisional processes in the interstellar gas, generating accurate data on the rate of molecular collisions is of salient interest to astronomical endeavors. The collision system focused on in this study is He-HD, an atom-diatom system in which He collides with HD. We are primarily interested in the cooling capabilities of this system, as these species are predicted to have played an important role in the formation of primordial stars, which emerged from a background composed solely of Hydrogen, Helium, and their compounds. HD is being investigated because it has a finite dipole moment and is hence a powerful radiator, and He due to its relative abundance in the early universe. Using a hybrid OpenMP/MPI adaption (vrrm) of a public-domain scattering package, cross sections for He-HD collisions are computed for a swathe of both rotational and vibrational states across a range of relevant kinetic energies, then integrated to produce rate coefficients. Due to the vast computational requirements for performing these operations, the use of high-powered computational resources is a necessity.
Acknowledgements
The work of CV was funded by a UGA Center for Undergraduate Research Opportunities award. We thank the University of Georgia GACRC and NERSC at Lawrence-Berkeley for computational resources and Brendan McLaughlin for assistance.
62 31 Full-dimensional Quantum Dynamics of CO, CN, SiO, and CS in Collisions with H2 Benhui Yang1, P. Zhang2, Chen Qu3, P. C. Stancil1, J. M. Bowman3, N. Balakrishnan4, R. C. Forrey5 1 Department of Physics and Astronomy, University of Georgia 2 Department of Chemistry, Duke University 3 Department of Chemistry, Emory University 4 Department of Chemistry, University of Nevada, Las Vegas 5 Department of Physics, Penn State University, Berks Campus
Corresponding author email: [email protected]
Molecular collisional rate coefficients are required to interpret astrophysical spectra of molecular gas not in local thermodynamic equilibrium. In cold environments such as the interstellar medium
(ISM), the dominant collision partner is primarily H2. Here we give an overview of our work on full-dimensional quantum dynamics studies of CO, CN, SiO, and CS in collisions with H2 which are of astrophysical importance, but for which vibrational, and in some cases rotational, excitation data are limited or nonexistent. We calculated the six-dimensional (6D) potential energy surfaces (PESs) using the ab initio CCSD(T) method. A invariant polynomial method was applied to fit the PESs analytically in 6D. For the first time we report full-dimensional quantum close-coupling calculation of rovibrational quenching cross sections and rate coefficients for these four systems. The calculated cross sections and rate coefficients are benchmarked with experiments and compared with previous theoretical results when available. The present rate coefficients for astrophysically relevant temperatures will enhance the scientific return from past, current, and future IR/submm observations with JWST, ISO, Spitzer, SOFIA, and Herschel, as well as other planned IR/submm telescopes.
Acknowledgements
Work at UGA and Emory was supported by NASA grant NNX16AF09G, at UNLV by NSF Grant No. PHY-1505557, and at Penn State by NSF Grant No. PHY-1503615.
63 32 Molecular data for hydrogen plasmas Mark Zammit Theoretical Division, Los Alamos National Laboratory
Recently we have embarked on the projects of calculating ab initio electron- and photon- molecule data of important diatomics. I will present results on the hydrogen molecule H2, its + ion H2 , the isotopologues, and discuss possible implications of these new results. To model electron-molecule collisions we have developed the ab initio molecular convergent close-coupling method [1−3]. Results from these studies are the first of their kind: calculating cross sections of all electronically driven processes and explicitly demonstrating convergence of the cross sections over a broad range of impact energies. Generally, the results are in good agreement with experiments, however, for some major processes large discrepancies are seen with generally accepted” and used data. For example, we see are factor of two difference for the direct electron-impact dissociation [2] process of H2 . For the photon-molecule project, we have recently developed our own code with the goal of calculating comprehensive opacity tables that are accurate across the entire range of temperature space, from molecular dominated opacities through to ion dominated opacities. + [4] Recently we calculated state-resolved photodissociation cross sections of H2 via the electronically excited states, and investigated isotopic effects. We also explored radiative association via excited states, which significantly enhances the cross section. References:
References
[1] M. C. Zammit et al. Phys. Rev. Lett. 116, 233201 (2016). [2] M. C. Zammit et al. Phys. Rev. A 95, 022708 (2017). [3] M. C. Zammit et al. Phys. Rev. A 90, 022711 (2014). [4] M. C. Zammit et al. Astrophys. J. 851, 64 (2017).
64 33 6. Molecular Spectra
High-Resolution Supersonic Jet Spectroscopy of Interstellar PAHs and PAH-related Analogs - Astronomical Applications S. Bejaoui1,2, F. Salama1 1NASA Ames Research Center, Moffett Field, CA 2Bay Area Environmental Research Institute, Moffett Field, CA
Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in space and most astronomical spectra, from the interstellar medium (ISM) to distant galaxies, including regions of massive star formation, the general ISM, and star forming spiral galaxies out to red-shifts of z > 4, are dom- inated by their ubiquitous infrared emission features (UIBs or ”PAH bands” as they are now commonly dubbed). Whether the PAH bands are intimately associated with the object, or fore- ground/background confounding features, they will have to be understood, separated from other features in the spectra, and analyzed for the information they contain on the physical and chemical properties of their surrounding environments. High-resolution laboratory spectra of PAHs and PAH related species measured in astrophysically- relevant environment are critical to answer these questions. The most challenging task is to re- produce, as closely as technically possible, the physical and chemical conditions that are present in space (i.e., cold gas phase molecules and ions, isolated in a collision-free environment). Com- parable conditions can be achieved using the cosmic simulation chamber (COSmIC) developed at NASA Ames. COSmIC allows to measure gas phase spectra of neutral and ionized interstellar PAH analogs by associating a molecular beam with a soft ionizing discharge that generates a cold plasma expansion (100 K) [1]. Using the highly sensitive Cavity Ring Down Spectroscopy (CRDS) technique, absorption spectra of PAHs and PAH derivatives seeded in Ar supersonic jets expansion are measured in the NUV-Vis-NIR region [2 for a review]. The resulting spectra provide a critical tool to identify and characterize specific molecules or ions in astrophysical environments. We in- tend to expand the capabilities of our current CRDS system to the NIR and MIR up to 3.5 µm in order to provide accurate high-resolution laboratory spectra that will help validate the extensive NASA Ames’ PAH database (PAHdb) and will greatly benet the interpretation of future JWST NIRSpec observational data. We also intend to implement two highly sensitive optical diagnostics, Laser Induced Fluorescence (LIF) and Laser Induced Incandescence (LII) in COSmIC in order to investigate the emission spectral signatures of cosmic molecules and grain analogs. The emission database of PAHs, PAH derivatives, PAH-clusters, and nanoparticles in the UV-NIR region is highly needed to assess the hypothesis of PAHs and PAH-related species as carriers of the blue luminescence, the extended red emission, and cometary emission.
65 References
[1] Tan, X. and Salama, F. (2005b), J. Chem. Phys. 123, 014312. [2] Salama, F., Galazutdinov, G. A., Krelowski, J., Biennier, L., Beletski, Y. and Song, I.-O (2011), The Astrophys. J. 728, 154.
Acknowledgements
This research is supported by the APRA Program of NASA SMD. The authors acknowledge the technical support of E. Quigley.
66 34 Dynamics of Pure and N-substituted Cyclic Aromatic Hydrocarbon Formation in the Gas-Phase, and Their Spectral Characterization from Microwave to Ultraviolet Partha Bera NASA Space Science and Astrobiology at Ames
The processes by which complex organic molecules including large polycyclic aromatic hy- drocarbons, known to be ubiquitous in the interstellar medium and accounting for a significant portion of total carbon in the universe, is thus far unknown. Organic molecules are found in diverse astrophysical environments, most notably in molecular clouds and hot cores. Molecular ions, including positive and negative ions, are abundant in the high radiation fields present in star forming regions. Barrierless ion-molecule interactions may play a major role in guiding molecules towards each other and initiating reactions. We study neutral as well as ion-neutral condensa- tion pathways to determine whether they are a viable means of forming large pure hydrocarbon molecules, nitrogen-containing carbonaceous chains, and cyclic compounds, by employing a variety of quantum chemical methods including coupled cluster and density functional theory methods. Where possible, the results from our calculations are compared with the results from experimental studies such as plasma discharge and ion-mobility experiments. We have investigated the process of growth, structural features, nature of bonding, reaction mechanisms, and spectroscopic properties of the ensuing products after pairing carbon, hydrogen, and nitrogen-containing precursors. The deliverables include new reaction pathways, rate constants, accurate ro-vibrational, and electronic spectra. Ab-initio molecular dynamics trajectory studies of the ion-neutral association pathways involving pure-carbon and nitrogen-containing precursors spanning several nanoseconds at various temperatures reveal interesting details about the cyclic molecule formation process, and also their limitations.
References
P. P. Bera, Martin Head-Gordon, and Timothy J. Lee Astron & Astrophys. 535, A74 (2011) P. P. Bera, M. Head-Gordon, and T. J. Lee, 15, 2012-2023, Phys. Chem. Chem. Phys. (2013) A. Hamid, P. P. Bera, T. J. Lee, S. G. Aziz, A. O. Alioub, and M. S. El-Shal, 5, 3392 (2014) P. P. Bera, R. Peverati, M. Head-Gordon, and T. J. Lee, Phys Chem Chem Phys, 17, 1859 (2015) R. Peverati, P. P. Bera, Martin Head-Gordon and Timothy J. Lee, Astrophys. J., 830, 128 (2016) T. Stein, P. P. Bera, T. J. Lee, and M. Head-Gordon, In preparation (2018)
67 35 High Resolution IR/Far-IR Spectra and Molecular Constants for 13C & D Substituted Propane Isotopologues Stephen Daunt Physics department, University of Tennessee - Knoxville
We have an ongoing project to obtain and analyze high resolution IR and Far-IR spectra of singly substituted 13C and D isotopologues of propane. Spectra have been run on the Bruker IFS 125 HR on the Far-IR beamline at the Canadian Light Source synchrotron. Bands corresponding to those already detected on Titan by Voyager and Cassini for the normal species of propane are one of our main aims. The other region of concentration is the lowest vibrational (non-torsion) mode near 360 cm−1 that is in the THz region and is unpertubed. This band has allowed us to obtain accurate rotational constants through 6th order for the different species. With these we hope to predict rotational lines that can be used in radio astronomy searches for these isotopic species in the ISM and planetary atmospheres.
68 36 Infrared Spectroscopy of Disilicon-Carbide: The ν3 Vibrational Band Guido W. Fuchs Laboratory Astrophysics, University Kassel, Germany
Formation of interstellar dust grains is not fully understood. Up-to-date small silicon and carbon containing molecules are thought as important building blocks of interstellar grains. Some of them have been detected in circumstellar environments of late-type stars by means of rotational spectroscopy e.g., SiC, SiC2, Si2C, c-SiC3, SiC4, while centro-symmetric species, e.g., C3,C4,C5, Si2C3, can only be detected by vibrational transitions, mainly in the infrared. In view of a new generation of high resolution infrared telescope instruments, e.g., EXES (Echelon-Cross-Echelle Spectrograph) onboard SOFIA (Observatory for Infrared Astronomy) and TEXES (Texas Echelon Cross Echelle Spectrograph) at the Gemini-North observatory, accurate laboratory data of small silicon-carbides in the infrared region are of high demand. In this contribution we present first −1 laboratory data of the Si2C asymmetric stretching mode at 1200 cm . A pulsed Nd:YAG-laser is used to vaporize a solid target of silicon exposed to a dilute sample of methane in helium buffer gas.
Si2C is formed in an adiabatic expansion of a supersonic jet and is probed by radiation of a quantum cascade laser which allows for rotationally resolved spectra. Around 150 absorption lines have been assigned to the asymmetric stretching vibration (v3) of Si2C, and derived molecular parameters are in excellent agreement with ab initio calculations. In a global fit recently published laboratory and astronomical data were taken into account. Our new results allow for identification of Si2C by means of high resolution infrared astronomy towards the warm background of carbon-rich stars.
69 37 Accurate and Consistent Prediction of Molecular IR Line Lists Based on Ab Initio Theory and High-Resolution Experimental Data Timothy Lee NASA Ames Research Center
In the last 10 years, the prediction-oriented ”best theory + high-resolution experimental data” strategy has been extended from water to NH3, CO2, and SO2. To compute the molecular infrared (IR) opacity, the accuracy of experimental line positions is combined with the consistency of high-quality ab initio theory. The Ames IR line lists computed on the empirically refined ab initio potential energy surface go beyond the reproduction of existing data to make predictions as accurate as 0.01-0.02 cm−1 for line positions and σ< 5 − 10% for line intensities. They provide valuable reference data and assignments for missing IR bands or minor isotopologues, identify the defects and unreliable extrapolations of existing effective Hamiltonian (EH) models, and improve molecular IR opacity databases. Recent experiments have verified the accuracy, consistency, and completeness of the Ames IR list predictions. Examples are given to demonstrate the EH database deficiencies, experimental difficulties, and the prediction accuracy and consistency of our work. Our latest study has pushed the strategy to a higher level: the microwave spectra of the SO2 minor isotopologues can be predicted with 1-5 MHz accuracy in the range of J < 20 and Ka < 10−15, and 0.01 − 0.02 MHz for the rotational constants A0/B0/C0. Ames IR intensity predictions have very high consistency across all isotopologues. These data provide quality control over experimental data or effective dipole moment models, and allow future ”finement” on intensities when much more accurate experimental intensity data become available. See http://huang.seti.org for the latest updates of the Ames molecular IR line lists.
70 38 Infrared Laser Spectroscopy of the Mass-selected Protonated CO Dimer Daniel Leicht University of Georgia
Protonated CO dimers are produced in a pulsed discharge supersonic expansion of a gas mix- ture of CO, hydrogen, and argon. The ions are pulse-extracted into a reflectron time-of-flight mass spectrometer, where they are analyzed and mass-selected. In the turning region of the reflectron, the ions are overlapped with an infrared laser beam and their vibrational spectrum is recorded by photo-dissociation of the argon-tagged species. The infrared spectra of the H and D isotopologues were recorded in the wavelength region 500 − 3500cm−1. Several bands are observed for both isotopologues. Computational studies at the CCSD(T)/ANO1 level of theory analyze the geome- tries, energetics, and anharmonic frequencies of six stable isomers and their argon-tagged variants. Surprisingly, the comparison of the experimental data with the ab initio predictions suggests that the most stable isomer, the proton-bound dimer, is not formed in our experiment. Instead, one higher energy isomer is formed, which lies 5.9 kcal/mol higher in energy than the global minimum.
71 39 Infrared Photodissociation Spectroscopy of the + Exotic H6 Cation in the Gas Phase David McDonald II Department of Chemistry, University of Georgia
+ H6 is generated in a supersonic expansion via pulsed electrical discharge of hydrogen. Hn+ clusters are extracted into a reflectron time-of-flight mass spectrometer and probed with infrared + photodissociation spectroscopy (IRPD) in the 2050-4600 cm-1 region. H6 was mass selected and found to have three distinct photodissociation channels by loss of one hydrogen atom, one hydrogen molecule or both. Each channel results in different spectra as a result of mode specific dissociation channels. The ground 2D2d state is 4 kcal/mol lower in energy than the 2Cs state with a 7 kcal/mol barrier. We believe we are probing the D2d structure with the three Hm+ (m=3,4,5) fragment channels as a result of rapid interconversion between the two states after IR photon absorption.
72 40 From One to Two Dimensional Interstellar Carbon: A Synthesis of Laboratory, Observations, and Theory Brett McGuire National Radio Astronomy Observatory
In the last 50 years of astrochemical research, the realm of one-dimensional carbon chemistry (i.e. carbon chain molecules) has been well explored. Life, however, relies on two and three- dimensional carbon - branches, rings, bridges, and so forth. Here, we present the first rotational de- tection of a six-membered ring molecule in the interstellar medium (ISM), benzonitrile (c-C6H5CN), using deep Green Bank Telescope observations of TMC-1 combined with high-precision laboratory spectroscopy. We then explore the formation chemistry of this two-dimensional carbon molecule using a combined laboratory, quantum chemical, and modeling approach. We demonstrate the synthesis of cyclic species (benzene [c-C6H6] and benzonitrile) from simple, acyclic precursors, providing definitive evidence for facile bottom-up generation of two-dimensional carbon chemistry in the ISM. The results show that benzonitrile can already be used as a reliable proxy for the presence of benzene in the ISM, and that there may exist a much larger array of ’hidden’ aromatic species just beyond the current sensitivity of spectral surveys.
73 41 Internal conversion and intersystem crossing pathways in UV excited uracils and their implications in prebiotic chemistry Susanne Ullrich Department of Physics and Astronomy, University of Georgia
The photodynamic properties of molecules determine their ability to survive in harsh radiation environments and, as such, ultraviolet photostability may have been one of the selection pres- sures influencing the prebiotic chemistry on early Earth. Over the years, the photophysics of the canonical nucleobases have been studied extensively due to their importance as the genetic coding material of life and they are generally considered photostable. Here, we investigate the photody- namics of 2-thiouracil and 4-thiouracil, derivatives of the nucleobase uracil, using time-resolved photoelectron spectroscopy to assess the effect of heavy atom substitution on recently proposed intersystem crossing pathways that compete with internal conversion to the ground state. Trap- ping in the triplet manifold and intersystem crossing back to the ground state are potential factors contributing to the susceptibility of molecules to ultraviolet photodamage.
74 42 7. Interstellar Medium
Hot H2O and OH in the inner disk of the Herbig Ae/Be star HD 101412 Steven Adams Clemson university
We report the detection of hot H2O and OH emission from the Herbig Ae/Be star HD 101412 using the Cryogenic Infrared Echelle Spectrograph on the Very Large Telescope. Previous studies of Herbig Ae/Be stars have shown the presence of OH around some of these sources, but H2O has proven more elusive. While marginal water emission has been reported in the mid-infrared, and a few Herbig Ae/Be stars show water emission in the far-infrared, water emission near 2.9 microns has not been previously detected. We apply slab models to the ro-vibrational OH, H2O, and CO spectra of this source and show that the molecules are consistent with being cospatial. Our ability to detect unusually bright molecular emission from HD 101412 may be related to its nature as a lambda Boo star, i.e., a star whose photosphere is strongly depleted in refractory elements (Fe, Mg, Si) but has solar abundances of volatile elements (C, N, O). If the low abundance of refractories results from the selective accretion of gas relative to dust, the inner disk of HD 101412 should be strongly dust-depleted and its continuum more optically thin, enhancing its molecular emission. Our detection of C- and O-bearing molecules from the inner disk of HD 101412 is consistent with the expected presence in this scenario of abundant volatiles in the accreting gas.
75 43
Properties of Highly Rotationally Excited H2 in Photodissociation Regions Sally Cummings, Ziwei Zhang, Yier Wan, P. C. Stancil Department of Physics and Astronomy, University of Georgia
Corresponding author email: [email protected]
H2 is the dominant molecular species in the vast majority of interstellar environments and it plays a crucial role as a radiative coolant. In photodissociation regions, it is one of the primary emitters in the near to mid-infrared which are due to lines originating from highly excited rotational levels. However, collisional data for rotational levels j > 10 are sparse, particularly for H2-H2 collisions. Utilizing new calculations for para-H2 and ortho-H2 collisional rate coefficients with H2 for j as high as 30, we investigate the effects of the new results in standard PDR models with the spectral simulation package Cloudy. We also perform Cloudy models of the Orion Bar and use Radex to explore rotational line ratio diagnostics. The resulting dataset of H2 collisional data should find wide application to other molecular environments.
Acknowledgements
This work was supported by Hubble Space Telescope grant HST-AR-13899.001-A and NASA grants NNX15AI61G and NNX16AF09G.
76 44 The 2017 Release Cloudy Ferland, G. J1; Chatzikos, M.1; Guzm´an,F.1; Lykins, M. L.1; van Hoof, P. A. M.2; Williams, R. J. R.3; Abel, N. P.4; Badnell, N. R.5; Keenan, F. P.6; Porter, R. L.7; Stancil, P. C.7 1 University of Kentucky, Lexington, USA 2 Royal Observatory of Belgium 3 AWE plc, UK 4 University of Cincinnati, USA 5 University of Strathclyde, Glasgow, UK 6 Queens University Belfast, Belfast, UK 7 University of Georgia, USA
Corresponding author email: [email protected]
We describe the 2017 release of the spectral synthesis code Cloudy, summarizing the many improvements to the scope and accuracy of the physics which have been made since the previous release. Exporting the atomic data into external data files has enabled many new large datasets to be incorporated into the code. The use of the complete datasets is not realistic for most cal- culations, so we describe the limited subset of data used by default, which predicts significantly more lines than the previous release of Cloudy. This version is nevertheless faster than the previous release, as a result of code optimizations. We give examples of the accuracy limits using small mod- els, and the performance requirements of large complete models. We summarize several advances in the H- and He-like iso-electronic sequences and use our complete collisional-radiative models to establish the densities where the coronal and local thermodynamic equilibrium approximations work.
77 45 Looking at the recombination lines in Cloudy spectral code Francisco Guzman Department of Physics and Astronomy, University of Kentucky
I will discuss future advances in spectral code CLOUDY, as well as ongoing development that should be of interest to observers and modelers alike. Atomic data for H-like and He-like iso- sequences is being reviewed. In addition, the implementation in Cloudy of a matrix condensation method will permit calculations including a high number of Rydberg levels, and allow compu- tationally fast and reliable simulations of infrared and radio recombination lines. CLOUDY is developed interactively with, and in response to the necessities of the astronomical community.
78 46 Photodissociation of Diatomic Molecules in Interstellar Environments Ryan Pattillo1, P. C. Stancil1, R. C. Forrey2, J. F. Babb3, and B. M. McLaughlin4 1Department of Physics and Astronomy, University of Georgia 2 Penn State University, Berks Campus 3 Smithsonian Astrophysical Observatory 4 Queen’s University Belfast
Corresponding author email: [email protected]
Photodissociation occurs when a molecule absorbs a photon of light and breaks apart into separate atoms or molecules. The molecule is initially rotating and vibrating at a certain energy level, and it transitions to an excited, unbound state upon absorbing the photon. This process is a major source of molecular destruction in a variety of interstellar environments with a strong radiation field such as circumstellar disks, protoplanetary disks, and diffuse and translucent clouds. To reliably estimate the abundances of molecules in these regions, it is important to have accu- rate photodissociation rates. Typically, photodissociation rates for a molecule are computed for transitions from only its ground rotational-vibrational level. For the carbon monosulfide (CS) and silicon monoxide (SiO) molecules, we instead compute photodissociation cross sections for transi- tions from several thousand rotational-vibrational levels to excited molecular states. This yields comprehensive cross sections which can be applied to calculate accurate photodissociation rates in a wide range of interstellar environments. We achieve this computationally using a two-state quantum perturbation approach. A detailed look into the modeling of this process, as well as some example applications of the cross sections, is presented.
79 47 The Impact of New Atomic Data on Nebular Bromine, Rubidium, and Xenon Abundances Nick Sterling University of West Georgia
We present preliminary results from grids of models that simulate the Br, Rb, and Xe ionization balance in planetary nebulae (PNe, the ejecta of dying low mass stars). These neutron(n)-capture elements (atomic number Z > 30) can be enriched by s-process nucleosynthesis during the asymp- totic giant branch (AGB) evolutionary stage of PN progenitor stars. We have added recently computed photoionization, recombination, and charge transfer atomic data for these elements to Cloudy (Ferland et al. 2013, RMxA&A, 49, 137). We computed grids that span the parameter space of central star temperature and luminosity, nebular density, chemical composition, metal- licity, and dust physics found in PNe. Using correlations between the ionic fractions of observed Br, Rb, and Xe ions (and combinations thereof) and those of commonly detected light element ions, we have derived ”ionization correction factors” (ICFs), analytic prescriptions that correct for unobserved when converting ionic abundances to elemental abundances. In PNe that exhibit emission from multiple Br, Rb, and/or Xe ions in their optical and near-infrared spectra, we test the new ICF formulae to gauge their precision. The comparison for Br is complicated by the unphysically large Br abundances we derive in high-ionization PNe, suggesting that optical [Br III] and [Br IV] transitions suffer from unidentified blends in PNe with hot central stars.
Acknowledgements
We acknowledge support from NSF grant AST-1412928.
80 48 8. Laboratory Facilities
The University of Georgia Small Satellite Reserach Laboratory Nicholas Heavner University of Georgia
The UGA SSRL is a newly founded (2015) undergraduate research lab that is focused on building satellites with high performance computational units onboard. The lab has two separate missions scheduled to be launched by early 2020, one that has an adjustable multi spectral imager for Earth observations and another mission that has the capability of processing large image sets while on orbit. Both of these missions are laying the ground work for future space based payloads built by UGA.
81 49 The COsmic SImulation Chamber (COSmIC) at NASA Ames: a Multipurpose Laboratory Astrophysics Facility for the Support of NASAs Space Missions in the JWST Era Farid Salama 1, Ella Sciamma-O’Brien1,2, Salma Bejaoui1,2, and Lisseth Gavilan 1 1 NASA Ames Research Center, Moffett Field, CA 2 Bay Area Environmental Research Institute, Moffett Field, CA.
We describe the characteristics and the capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory[1]. COSmIC stands for Cosmic Simulation Chamber and is dedicated to the study of neutral and ionized molecules and nanoparticles under the low tempera- ture and high vacuum conditions that are required to simulate various space environments such as diffuse interstellar clouds, circumstellar outflows and planetary atmospheres. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions in the laboratory. The COSmIC experimental setup is composed of a Pulsed Discharge Nozzle (PDN) expansion, that generates a plasma in the stream of a jet-cooled super- sonic expansion (50-150 K), coupled to two high-sensitivity-, complementary in situ diagnostics: a cavity ring down spectroscopy (CRDS[2]) and laser induced fluorescence (LIF[3]) systems for photonic detection, and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection in real time[4]. Recent advances achieved in laboratory astrophysics using COSmIC will be presented. In particular, the progress that has been achieved (i) in the domain of the diffuse interstellar bands (DIBs[5]) and the ESO Diffuse Interstellar Bands Large Exploration Survey, EDIBLES[6,7], (ii) in monitoring, in the laboratory, the formation of circumstellar dust grains[8, 9] and (iii) in the study of planetary atmosphere aerosols[10, 11, 12] from their gas-phase molecular precursors. Plans for future laboratory experiments on interstellar molecules and grains will also be addressed, as well as the implications of the studies underway for astronomical observations (EDIBLES) and space mission (HST, JWST, SOFIA, ...) data analysis.
References
[1] Salama, F., Sciamma-O’Brien E., Contreras C., Bejaoui S. in IAU Proceedings Series (2018), in press. [2] Biennier, L., F. Salama, L.J. Allamandola and J. J. Scherer., J. Chem. Phys., 118, 7863 (2003). [3] Bejaoui S., F. Salama. E. Sciamma-OBrien, in IAU Proceedings Series 11, A29A, (2015). [4] Ricketts C., Contreras C., Walker, R., Salama F., Int. J. Mass Spec, 300, 26 (2011) [5] Salama F., Galazutdinov G., Krelowski J., Biennier L., Beletsky Y., In-Ok Song, ApJ, 728, 154 (2011)
82 [6] Cox, N.L.J. and the ESO EDIBLES Consortium, A&A, 606, A76 (2017) [7] Cami, J. and the ESO EDIBLES Consortium, ESO Messenger, in press (2018) [8] Cesar Contreras and Farid Salama, ApJ. Suppl. Ser., 208, 6 (2013) [9] NASA Press RELEASE 14-129: NASA Simulator Successfully Recreates Space Dust https://www.nasa.gov/press/2014/may/nasa-simulator-successfully-recreates-space-dust/ [10] Sciamma-O’Brien E., Ricketts C., and Salama F. Icarus, 243, 325 (2014) [11] Sciamma-O’Brien E., Upton K. and Salama F., Icarus, 289, 214 (2017) [12] Raymond A. W., Sciamma-OBrien E., Salama F., Mazur E., ApJ, 853, 107 (2018)
Acknowledgements
This research is supported by the APRA Program of NASA SMD. The authors acknowledge the technical support of E. Quigley. L.G. acknowledges the support of the NPP Fellowship program.
83 50 9. Nuclear Processes
Progress towards the Single Atom Microscope: measuring rare-reaction rates for nuclear astrophysics. Ben Loseth Department of Physics and Astronomy, Michigan State University
We propose a new method for measuring the rate of rare nuclear reactions by capturing the heavier atomic products in a noble gas solid. Once embedded in the transparent noble gas matrix, the products are selectively identified via laser fluorescence spectroscopy and individually counted via optical imaging to determine the reaction rate. Single atom sensitivity is feasible due to the noble gas matrix facilitating a Stokes shift between the emission and excitation spectrum of the product atoms, granting the possibility to carefully filter out the excitation light. The combination of a recoil separator, for isotopic selectivity and beam heat load reduction, and the tools and techniques borrowed from the fields of single molecule spectroscopy and superresolution imaging allows for a detecting scheme with near unity efficiency, a high degree of selectivity, and single atom sensitivity. This technique could be used to measure a number of astrophysically relevant reaction rates.
84 51 Connections between nuclear physics and the kilonova observations in neutron-star mergers Artemis Spyrou National Superconducting Cyclotron Laboratory, Michigan State University
Recently, gravitational wave facilities and telescopes around the world and in space observed for the first time a neutron-star merger event. These observations answered a lot of questions about the nature of these rare events but many questions are still open. In particular, the electro- magnetic observations of a ”kilonova” at different wavelengths was interpreted as the signal from the radioactive decay of heavy elements that are synthesized during the merger. While the elec- tromagnetic signals were studied for different wavelengths and over a long time, the interpretation still requires detailed knowledge of the involved microphysics. In this presentation I will focus on the important nuclear physics properties. I will discuss how they impact the kilonova signals, and what type of nuclear physics measurements are needed to better understand nucleosynthesis in neutron-star mergers.
85 52 10. Solar and Heliospheric
An Early prediction of 25th and 26th solar cycles Asheesh Bhargawa Department of Physics, University of Lucknow, India
The analysis of long memory processes in solar activity, space weather and other geophysical phenomena has been a major issue even after the enough available data. We have examined the data of three main solar parameters which are the sunspot numbers, 10.7 cm and the Lyman alpha index for the year 1976 2017. We have done the statistical test for persistence of solar activity based on the value of Hurst exponent (H) which is one of the most classical applied methods known as rescaled range analysis. We have discussed the efficiency of this methodology as well as prediction content for next two solar cycles that is for 25th and 26th solar cycle, based on long term memory. In the present study, Hurst exponent analysis has been used to investigate the persistence of above mentioned solar activity parameters and a simplex projection analysis have been used to predict the ascension time and the maximum number of counts for 25th and 26th solar cycle. For available dataset of the year 1976 2017, we have calculated H = 0.902, 0.949 and 0.965 for sunspot number, 10.7cm radio flux and Lyman alpha index respectively. Further we have calculated maximum number of counts for the sunspot numbers, F10.7cm index and Lyman alpha as 102.824.6, 137.258.9 and 4.521.6 respectively 25th solar cycle and for the 26th solar cycle the maximum values of these three parameters are 57.1612.7, 98.584.8 and 4.190.98 respectively. Using the simplex projection analysis, we have forecasted that the solar cycle 25th would start in the year 2021 (January) and would last up to the year 2031 (September) with its maxima in June 2024 and the solar cycle 26th would start in the year 2031 (October) and would last up to the year 2042 (July) with its maxima in September 2036.
86 53 On the statistical study of Solar flare effect and radio communication signals Kumud Pandey Lovely Professional University, Jalandhar, India
It is well known that interplanetary Coronal Mass Ejections (ICMEs) are the interplanetary counterparts of the Coronal Mass Ejections (CMEs. Based on the literatures, the possible in-situ signatures of the ICMEs are the strong magnetic field, rotated magnetic field, low plasma low proton temperature, expansion velocity profile, bidirectional electron streaming, lower energetic particle intensity and so on (Gopalswamy, 2006 and reference therein). It is noted that, none of these signatures can be observed by all ICMEs. So, different authors always used different criterion to identify the ICMEs from in-situ observations. Using different criterion, different lists about the ICMEs and their related structures (such as ICME like structures and so on) were compiled by different authors. Based on ICME catalogue, the statistical analysis of the ICMEs was extended to the solar maximum phase of solar cycle 24th. In the analysis of the annual variations of the different parameter of ICMEs .It is found that the number of ICMEs, the number of shocks, the percentage of ICMEs drove shocks, the magnetic field and plasma properties of ICMEs are well correlated with the solar cycle variation. The number of Magnetic Clouds(MCs) does not show well correlation with sunspot number. But, the percentage of the MCs in ICMEs shows good anti-correlation with the sunspot number. The comparison of various parameters of MCs with None-MC ICMEs are also done and it is found that the MCs are stronger than the None-MC ICMEs.
87 54 11. Star Formation
A Spectroastrometric Survey of Warm Gas in Disks around Young Stars Sean Brittain Department of Physics & Astronomy, Clemson University
We present high resolution NIR spectroscopy of CO around young stars acquired with iSHELL on the NASA IRTF. We compare our observations to previous studies and show how large format arrays enable spectroastrometric studies of gas on even modest aperture telescopes. We compare our spectra to previous observations and discuss how such observations have the potential to show signatures of actively accreting planets. We also discuss the prospects of continuing this survey with upgraded instruments on 8m class telescopes.
88 55 12. Hydrodynamics
Study of Accretion Disk Physics in the Laboratory Hantao Ji Princeton Plasma Physics Laboratory, Princeton University
A concise summary is given by this presentation on recent results from laboratory experiments at Princeton relevant to physics of accretion disks during star formation, energetic activity of cat- aclysmic variables, and Active Galactic Nuclei including quasars. The motivating problem there is the generation mechanism for the required turbulence in order to explain fast angular momentum transport. Two sister laboratory apparatuses were built to study two main competing candidate mechanisms: (1) a linear instability of magnetized and electrically conducting flow known as mag- netorotational instability (MRI); and (2) nonlinear hydrodynamic shear-flow instability. Both of these devices are novel in two respects: large Reynolds numbers (> 106) and multiple indepen- dently driven rings to minimize boundary effects. We have convincingly demonstrated negligible angular momentum transport in quasi-keplerian hydrodynamic flow, even after vigorous pertur- bations. This result has effectively invalidated the mechanisms based on nonlinear hydrodynamic turbulence, or at least its incompressible version. On the other hand, positively identifying MRI has been complicated by boundary effects and also by small MRI saturation levels due to weak drive. Recently, we have successfully implemented new electrically conducting endcaps to signif- icantly increase the MRI saturation levels based on numerical predictions. Initial results have confirmed effectiveness of conducting boundaries. Finally, I will highlight a novel experiment to demonstrate the MRI mechanism using a laboratory spring-mass analogue.
89 List of Participants
Name Institution Email
Steven Adams Clemson University [email protected] Kwame Appiah Ghana Atomic Energy Commission [email protected] Keith Arnaud NASA Goddard Space Flight Center [email protected] James Babb Smithsonian Astrophysical Observatory [email protected] Dmitri Babikov Marquette University [email protected] Jacob Beckham University of Georgia [email protected] Salma Bejaoui NASA Ames Research Center [email protected] Maria Teresa Belmonte Imperial College London [email protected] Partha Bera NASA NASA Ames Research Center [email protected] Peter Bernath Old Dominion University [email protected] Peter Bertone NASA [email protected] Asheesh Bhargawa University of Lucknow, India [email protected] Binod Bhattarai St. Xavier’s College, Nepal [email protected] Christiaan Boersma NASA Ames Research Center [email protected] Kyle Bowen Columbia University [email protected] Nancy Brickhouse Harvard-Smithsonian Center for Astrophys. [email protected] Sean Brittain Clemson University [email protected] Steven Bromley Clemson University [email protected] Nat Byrd University of Georgia [email protected] Frances Cashman University of South Carolina [email protected] Marios Chatzikos University of Kentucky [email protected] Renata Cumbee NASA Goddard Space Flight Center [email protected] Sally Cummings University of Georgia [email protected] Joseph Czekner Brown University joseph [email protected] Jayne Dailey University of Georgia [email protected] Stephen Daunt University of Tennessee - Knoxville [email protected] Marie-Lise Dubernet OBSERVATORY OF PARIS, France [email protected]
90 Michael Duncan University of Georgia [email protected] Paul Dunk Florida State University [email protected] Steven Federman University of Toledo [email protected] Gary Ferland University of Kentucky [email protected] Alicia Flowers University of Georgia [email protected] Christopher Fontes Los Alamos National Laboratory [email protected] Adam Foster Harvard-Smithsonian Center for Astrophys. [email protected] Guido W. Fuchs University Kassel, Germany [email protected] Amy Gall Clemson University [email protected] Lisseth Gavilan Universit´eVersailles St-Quentin, French [email protected] Thomas Gorczyca Western Michigan University [email protected] Harshal Gupta The National Science Foundation [email protected] Francisco Guzman University of Kentucky [email protected] Nicholas Heavner University of Georgia [email protected] Negar Heidarian The University of Toledo [email protected] Natalie Hell Lawrence Livermore National Laboratory [email protected] Pierre Hillenbrand Columbia University [email protected] Douglas Hudgins NASA [email protected] Anastashia Jebraeilli University of Georgia [email protected] Hantao Ji Princeton University [email protected] Mackenzie Joy University of Georgia [email protected] Tim Kallman NASA Goddard Space Flight Center [email protected] Matin Kaufmann Ruhr-University Bochum, Germany [email protected] Varsha Kulkarni University of South Carolina [email protected] William Latter NASA [email protected] Jinhee Lee University of Georgia [email protected] Timothy Lee NASA Ames Research Center [email protected] Daniel Leicht University of Georgia [email protected] Maurice Leutenegger NASA Goddard Space Flight Center [email protected]
91 Stuart Loch Auburn University [email protected] Ben Loseth Michigan State University [email protected] Joshua Marks University of Georgia [email protected] Andrew Mattioda NASA Ames Research Center [email protected] Ryan McArdle University of Georgia [email protected] Michael McCarthy Harvard University [email protected] David McDonald II University of Georgia [email protected] Brett McGuire National Radio Astronomy Observatory [email protected] Stefanie Milam NASA [email protected] Ansley Miller University of Georgia [email protected] W. James Morgan University of Georgia [email protected] Taisuke Nagayama Sandia National Laboratories [email protected] Gillian Nave NIST [email protected] Kumud Pandey Lovely Professional University, India [email protected] Ryan Pattillo University of Georgia [email protected] Els Peeters University of Western Ontario, Canada [email protected] Robert Petre NASA Goddard Space Flight Center [email protected] Michael S. Pindzola Auburn University [email protected] Klaus Pontoppidan Space Telescope Science Institute (STScI) [email protected] Yuri Ralchenko NIST [email protected] Debra Richman Michigan State University [email protected] Brandon Rittgers University of Georgia [email protected] Daniel Wolf Savin Columbia University [email protected] Farid Salama NASA Ames Research Center [email protected] Alex Scherer University of Wisconsin-Madison [email protected] Ella Sciamma O’Brien NASA Ames Research Center [email protected] Lauren Sgro University of Georgia [email protected] Chintan Shah Max-Planck-Institut f¨urKernphysik Heidelberg [email protected] Alan Smale NASA Goddard Space Flight Center [email protected]
92 Kimberly Ennico Smith NASA [email protected] Artemis Spyrou Michigan State University [email protected] Phillip Stancil University of Georgia [email protected] Nick Sterling University of West Georgia [email protected] Lisa Storrie Lombardi NASA [email protected] Amanda Stricklan University of Georgia [email protected] Jason Terry University of Georgia [email protected] Frank Timmes Arizona State University [email protected] Susanne Ullrich University of Georgia [email protected] Clark Veazey University of Georgia [email protected] Philipp Wagner University of Georgia [email protected] Glenn Wahlgren Space Telescope Science Institute [email protected] Yier Wan University of Georgia [email protected] Ruihan Wang University of Georgia [email protected] Susanna Widicus Weaver Emory University [email protected] Ian Webster University of Georgia [email protected] Laurent Wiesenfeld Universit´eGrenoble-Alpes, France [email protected] Benhui Yang University of Georgia [email protected] Mark Zammit Los Alamos National Laboratory [email protected] Ziwei Zhang University of Georgia [email protected]
93