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Refereed Publications That Name
59 Refereed Publications Since 2011 with Named Co-Authors who are NASA Citizen Scientists Compiled by Marc Kuchner February 2021 Authors in bold are citizen scientists. Aurorasaurus Semeter, J., Hunnekuhl, M., MacDonald, E., Hirsch, M., Zeller, N., Chernenkoff, A., & Wang, J. (2020). The mysterious green streaks below STEVE. AGU Advances, 1, e2020AV000183. https://doi.org/10.1029/2020AV000183 Hunnekuhl, M., & MacDonald, E. (2020). Early ground‐based work by auroral pioneer Carl Størmer on the high‐altitude detached subauroral arcs now known as “STEVE”. Space Weather, 18, e2019SW002384. https://doi.org/10.1029/2019SW002384 S. B. Mende. B. J. Harding, & C. Turner. “Subauroral Green STEVE Arcs: Evidence for Low- Energy Excitation” Geophysical Research Letters, Volume 46, Issue 24, Pages 14256-14262 (2019) http://doi.org/10.1029/2019GL086145 S. B. Mende. & C. Turner. “Color Ratios of Subauroral (STEVE) Arcs” Journal of Geophysical Research (Space Physics),Volume 124, Issue 7, Pages 5945-5955 (2019) http://doi.org/10.1029/2019JA026851 Y. Nishimura, Y., B, Gallardo-Lacourt, B., Y, Zou, E. Mishin, D.J. Knudsen, E. F. Donovan, V. Angelopoulos, R. Raybell, “Magnetospheric Signatures of STEVE: Implications for the Magnetospheric Energy Source and Interhemispheric Conjugacy” Geophysical Research Letters, Volume 46, Issue 11, Pages 5637-5644 (2019) Elizabeth A. MacDonald, Eric Donovan, Yukitoshi Nishimura, Nathan A. Case, D. Megan Gillies, Bea Gallardo-Lacourt, William E. Archer, Emma L. Spanswick, Notanee Bourassa, Martin Connors, Matthew Heavner, Brian Jackel, Burcu Kosar, David J. Knudsen, Chris Ratzlaff and Ian Schofield, “New science in plain sight: Citizen scientists lead to the discovery of optical structure in the upper atmosphere” Science Advances, vol. -
Exors and the Stellar Birthline Mackenzie S
A&A 600, A133 (2017) Astronomy DOI: 10.1051/0004-6361/201630196 & c ESO 2017 Astrophysics EXors and the stellar birthline Mackenzie S. L. Moody1 and Steven W. Stahler2 1 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA e-mail: [email protected] 2 Astronomy Department, University of California, Berkeley, CA 94720, USA e-mail: [email protected] Received 6 December 2016 / Accepted 23 February 2017 ABSTRACT We assess the evolutionary status of EXors. These low-mass, pre-main-sequence stars repeatedly undergo sharp luminosity increases, each a year or so in duration. We place into the HR diagram all EXors that have documented quiescent luminosities and effective temperatures, and thus determine their masses and ages. Two alternate sets of pre-main-sequence tracks are used, and yield similar results. Roughly half of EXors are embedded objects, i.e., they appear observationally as Class I or flat-spectrum infrared sources. We find that these are relatively young and are located close to the stellar birthline in the HR diagram. Optically visible EXors, on the other hand, are situated well below the birthline. They have ages of several Myr, typical of classical T Tauri stars. Judging from the limited data at hand, we find no evidence that binarity companions trigger EXor eruptions; this issue merits further investigation. We draw several general conclusions. First, repetitive luminosity outbursts do not occur in all pre-main-sequence stars, and are not in themselves a sign of extreme youth. They persist, along with other signs of activity, in a relatively small subset of these objects. -
2008 Smithsonian Folklife Festival
Smithsonian Folklife Festival records: 2008 Smithsonian Folklife Festival CFCH Staff 2017 Ralph Rinzler Folklife Archives and Collections Smithsonian Center for Folklife and Cultural Heritage 600 Maryland Ave SW Washington, D.C. [email protected] https://www.folklife.si.edu/archive/ Table of Contents Collection Overview ........................................................................................................ 1 Administrative Information .............................................................................................. 1 Historical note.................................................................................................................. 2 Scope and Contents note................................................................................................ 2 Arrangement note............................................................................................................ 2 Introduction....................................................................................................................... 3 Names and Subjects ...................................................................................................... 4 Container Listing ............................................................................................................. 6 Series 1: Program Books, Festival Publications, and Ephemera, 2008................... 6 Series 2: Bhutan: Land of the Thunder Dragon....................................................... 7 Series 3: NASA: Fifty Years and Beyond............................................................. -
Star Formation in the “Gulf of Mexico”
A&A 528, A125 (2011) Astronomy DOI: 10.1051/0004-6361/200912671 & c ESO 2011 Astrophysics Star formation in the “Gulf of Mexico” T. Armond1,, B. Reipurth2,J.Bally3, and C. Aspin2, 1 SOAR Telescope, Casilla 603, La Serena, Chile e-mail: [email protected] 2 Institute for Astronomy, University of Hawaii at Manoa, 640 N. Aohoku Place, Hilo, HI 96720, USA e-mail: [reipurth;caa]@ifa.hawaii.edu 3 Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309, USA e-mail: [email protected] Received 9 June 2009 / Accepted 6 February 2011 ABSTRACT We present an optical/infrared study of the dense molecular cloud, L935, dubbed “The Gulf of Mexico”, which separates the North America and the Pelican nebulae, and we demonstrate that this area is a very active star forming region. A wide-field imaging study with interference filters has revealed 35 new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41 Hα emission- line stars, 30 of them new. A small cluster of partly embedded pre-main sequence stars is located around the known LkHα 185-189 group of stars, which includes the recently erupting FUor HBC 722. Key words. Herbig-Haro objects – stars: formation 1. Introduction In a grism survey of the W80 region, Herbig (1958) detected a population of Hα emission-line stars, LkHα 131–195, mostly The North America nebula (NGC 7000) and the adjacent Pelican T Tauri stars, including the little group LkHα 185 to 189 located nebula (IC 5070), both well known for the characteristic shapes within the dark lane of the Gulf of Mexico, thus demonstrating that have given rise to their names, are part of the single large that low-mass star formation has recently taken place here. -
SXP 1062, a Young Be X-Ray Binary Pulsar with Long Spin Period⋆
A&A 537, L1 (2012) Astronomy DOI: 10.1051/0004-6361/201118369 & c ESO 2012 Astrophysics Letter to the Editor SXP 1062, a young Be X-ray binary pulsar with long spin period Implications for the neutron star birth spin F. Haberl1, R. Sturm1, M. D. Filipovic´2,W.Pietsch1, and E. J. Crawford2 1 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany e-mail: [email protected] 2 University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW1797, Australia Received 31 October 2011 / Accepted 1 December 2011 ABSTRACT Context. The Small Magellanic Cloud (SMC) is ideally suited to investigating the recent star formation history from X-ray source population studies. It harbours a large number of Be/X-ray binaries (Be stars with an accreting neutron star as companion), and the supernova remnants can be easily resolved with imaging X-ray instruments. Aims. We search for new supernova remnants in the SMC and in particular for composite remnants with a central X-ray source. Methods. We study the morphology of newly found candidate supernova remnants using radio, optical and X-ray images and inves- tigate their X-ray spectra. Results. Here we report on the discovery of the new supernova remnant around the recently discovered Be/X-ray binary pulsar CXO J012745.97−733256.5 = SXP 1062 in radio and X-ray images. The Be/X-ray binary system is found near the centre of the supernova remnant, which is located at the outer edge of the eastern wing of the SMC. The remnant is oxygen-rich, indicating that it developed from a type Ib event. -
Lunar and Planetary Information Bulletin No. 161 (July 2020)
THE DEEP SPACE NETWORK: NASA’s Link to the Solar System Featured Story | From the Desk of Lori Glaze | Meeting Highlights | News from Space | Spotlight on Education In Memoriam | Milestones | New and Noteworthy | Calendar LUNAR AND PLANETARY INFORMATION BULLETIN July 2020 Issue 161 FEATURED STORY THE DEEP SPACE NETWORK: NASA’s Link to the Solar System Note from the Editors: This issue’s lead article is the tenth in a series of reports describing the history and current activities of the planetary research facilities funded by NASA and located nationwide. This issue features the Deep Space Network, a worldwide network of spacecraft communication facilities that supports NASA’s interplanetary spacecraft missions. — Paul Schenk and Renée Dotson From Mercury to Pluto (and beyond) we tary robotic space missions. Other space system and ultimately, our place within it. have marveled at the stunning vistas agencies, such as Europe’s ESA and found throughout our solar system. Japan’s JAXA also use the DSN by coop- The forerunner of the DSN was estab- From the erupting volcanos on Io to the erative agreements. The DSN consists of lished in January, 1958, when the Jet glorious rings of Saturn, it is easy to three major facilities spaced equidistant Propulsion Laboratory, or JPL‚ then forget that we would never have an about from each other‚ approximately 120 under contract to the U.S. Army‚ degrees apart in longitude‚ around the deployed portable radio tracking stations but for one key global NASA facility, none world. These sites are at Goldstone, near in Nigeria, Singapore, and California. -
The Birth and Evolution of Brown Dwarfs
The Birth and Evolution of Brown Dwarfs Tutorial for the CSPF, or should it be CSSF (Center for Stellar and Substellar Formation)? Eduardo L. Martin, IfA Outline • Basic definitions • Scenarios of Brown Dwarf Formation • Brown Dwarfs in Star Formation Regions • Brown Dwarfs around Stars and Brown Dwarfs • Final Remarks KumarKumar 1963; 1963; D’Antona D’Antona & & Mazzitelli Mazzitelli 1995; 1995; Stevenson Stevenson 1991, 1991, Chabrier Chabrier & & Baraffe Baraffe 2000 2000 Mass • A brown dwarf is defined primarily by its mass, irrespective of how it forms. • The low-mass limit of a star, and the high-mass limit of a brown dwarf, correspond to the minimum mass for stable Hydrogen burning. • The HBMM depends on chemical composition and rotation. For solar abundances and no rotation the HBMM=0.075MSun=79MJupiter. • The lower limit of a brown dwarf mass could be at the DBMM=0.012MSun=13MJupiter. SaumonSaumon et et al. al. 1996 1996 Central Temperature • The central temperature of brown dwarfs ceases to increase when electron degeneracy becomes dominant. Further contraction induces cooling rather than heating. • The LiBMM is at 0.06MSun • Brown dwarfs can have unstable nuclear reactions. Radius • The radii of brown dwarfs is dominated by the EOS (classical ionic Coulomb pressure + partial degeneracy of e-). • The mass-radius relationship is smooth -1/8 R=R0m . • Brown dwarfs and planets have similar sizes. Thermal Properties • Arrows indicate H2 formation near the atmosphere. Molecular recombination favors convective instability. • Brown dwarfs are ultracool, fully convective, objects. • The temperatures of brown dwarfs can overlap with those of stars and planets. Density • Brown dwarfs and planets (substellar-mass objects) become denser and cooler with time, when degeneracy dominates. -
Paul Hertz NASA Town Hall with Bonus Material
Paul Hertz Dominic Benford Felicia Chou Valerie Connaughton Lucien Cox Jeanne Davis Kristen Erickson Daniel Evans Michael Garcia Ellen Gertsen Shahid Habib Hashima Hasan Douglas Hudgins Patricia Knezek Elizabeth Landau William Latter Michael New Mario Perez Gregory Robinson Rita Sambruna Evan Scannapieco Kartik Sheth Eric Smith Eric Tollestrup NASA Town Hall with bonus material AAS 235th Meeting | January 5, 2020 Paul Hertz Director, Astrophysics Division Science Mission Directorate @PHertzNASA Posted at http://science.nasa.gov/astrophysics/documents 1 2 Spitzer 8/25/2003 Formulation + SMEX/MO (2025), Implementation MIDEX/MO (2028), etc. Primary Ops ] Extended Ops SXG (RSA) 7/13/2019 Webb Euclid (ESA) 2021 WFIRST 2022 Mid 2020s Ariel (ESA) 2028 XMM-Newton Chandra (ESA) TESS 7/23/1999 12/10/1999 4/18/2018 NuSTAR 6/13/2012 Fermi IXPE Swift 6/11/2008 2021 11/20/2004 XRISM (JAXA) SPHEREx 2022 2023 Hubble ISS-NICER GUSTO 4/24/1990 6/3/2017 2021 SOFIA Full Ops 5/2014 + Athena (early 2030s), Revised November 24, 2019 LISA4 (early 2030s) Outline • Celebrate Accomplishments § Mission Milestones • Committed to Improving § Building an Excellent Workforce § Research and Analysis Initiatives • Program Update § Research & Analysis, Technology, Fellowships § ROSES-2020 Preview • Missions Update § Operating Missions and Senior Review § Webb, WFIRST § Other missions • Planning for the Future § FY20 Budget § Project Artemis § Supporting Astro2020 § Creating the Future 5 NASA Astrophysics Celebrate Accomplishments https://www.nasa.gov/2019 7 NASA Astrophysics -
Issue 105, February 2006
GGOINGOING TOTO PPLUTOLUTO:: TTHEHE NNEWEW HHORIZONSORIZONS MMISSIONISSION — Paul Schenk, Lunar and Planetary Institute Fastest man-made object to leave Earth. Fastest flight past the Moon’s orbit. It was a day of superlatives, but it didn’t come easy for those watching. Going back to 1992, there have been at least three attempts to begin building a spacecraft to go to Pluto, the “last” unexplored planet. Only in 2001 was a team and mission chosen that would finally make it past the hurdles of Congress, the Office of Management and Budget (OMB), and NASA management. Once the process finally began, it took only five years from the call for mission proposals to launch day. Once on the launch pad, things went relatively smoothly until launch day itself, originally set for January 10 but then pushed back until January 17. Although involved with NASA for more than 20 years now, I had never personally witnessed a launch. We arrived at Kennedy Space Center early on the 17th, as directed, and waited outside to the music of 2001 — A Space Odyssey and a recording of the voice of Neil Armstrong walking on the Moon. We met many of our friends from the team, and together we boarded the fleet of buses to the viewing area. It was warm but windy, a bad omen. The launch window was only three hours long and peak winds kept exceeding the tolerable limits for launch. Every 15 minutes or so the launch commentator announced that the launch time was being pushed back again in hopes the winds would subside. -
Chapter 1 a Theoretical and Observational Overview of Brown
Chapter 1 A theoretical and observational overview of brown dwarfs Stars are large spheres of gas composed of 73 % of hydrogen in mass, 25 % of helium, and about 2 % of metals, elements with atomic number larger than two like oxygen, nitrogen, carbon or iron. The core temperature and pressure are high enough to convert hydrogen into helium by the proton-proton cycle of nuclear reaction yielding sufficient energy to prevent the star from gravitational collapse. The increased number of helium atoms yields a decrease of the central pressure and temperature. The inner region is thus compressed under the gravitational pressure which dominates the nuclear pressure. This increase in density generates higher temperatures, making nuclear reactions more efficient. The consequence of this feedback cycle is that a star such as the Sun spend most of its lifetime on the main-sequence. The most important parameter of a star is its mass because it determines its luminosity, ef- fective temperature, radius, and lifetime. The distribution of stars with mass, known as the Initial Mass Function (hereafter IMF), is therefore of prime importance to understand star formation pro- cesses, including the conversion of interstellar matter into stars and back again. A major issue regarding the IMF concerns its universality, i.e. whether the IMF is constant in time, place, and metallicity. When a solar-metallicity star reaches a mass below 0.072 M ¡ (Baraffe et al. 1998), the core temperature and pressure are too low to burn hydrogen stably. Objects below this mass were originally termed “black dwarfs” because the low-luminosity would hamper their detection (Ku- mar 1963). -
The UV Perspective of Low-Mass Star Formation
galaxies Review The UV Perspective of Low-Mass Star Formation P. Christian Schneider 1,* , H. Moritz Günther 2 and Kevin France 3 1 Hamburger Sternwarte, University of Hamburg, 21029 Hamburg, Germany 2 Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research; Cambridge, MA 02109, USA; [email protected] 3 Department of Astrophysical and Planetary Sciences Laboratory for Atmospheric and Space Physics, University of Colorado, Denver, CO 80203, USA; [email protected] * Correspondence: [email protected] Received: 16 January 2020; Accepted: 29 February 2020; Published: 21 March 2020 Abstract: The formation of low-mass (M? . 2 M ) stars in molecular clouds involves accretion disks and jets, which are of broad astrophysical interest. Accreting stars represent the closest examples of these phenomena. Star and planet formation are also intimately connected, setting the starting point for planetary systems like our own. The ultraviolet (UV) spectral range is particularly suited for studying star formation, because virtually all relevant processes radiate at temperatures associated with UV emission processes or have strong observational signatures in the UV range. In this review, we describe how UV observations provide unique diagnostics for the accretion process, the physical properties of the protoplanetary disk, and jets and outflows. Keywords: star formation; ultraviolet; low-mass stars 1. Introduction Stars form in molecular clouds. When these clouds fragment, localized cloud regions collapse into groups of protostars. Stars with final masses between 0.08 M and 2 M , broadly the progenitors of Sun-like stars, start as cores deeply embedded in a dusty envelope, where they can be seen only in the sub-mm and far-IR spectral windows (so-called class 0 sources). -
The FIRST STARS in the UNIVERSE WERE TYPICALLY MANY TIMES More Massive and Luminous Than the Sun
THEFIRST STARS IN THE UNIVERSE Exceptionally massive and bright, the earliest stars changed the course of cosmic history We live in a universe that is full of bright objects. On a clear night one can see thousands of stars with the naked eye. These stars occupy mere- ly a small nearby part of the Milky Way galaxy; tele- scopes reveal a much vaster realm that shines with the light from billions of galaxies. According to our current understanding of cosmology, howev- er, the universe was featureless and dark for a long stretch of its early history. The first stars did not appear until perhaps 100 million years after the big bang, and nearly a billion years passed before galaxies proliferated across the cosmos. Astron- BY RICHARD B. LARSON AND VOLKER BROMM omers have long wondered: How did this dramat- ILLUSTRATIONS BY DON DIXON ic transition from darkness to light come about? 4 SCIENTIFIC AMERICAN Updated from the December 2001 issue COPYRIGHT 2004 SCIENTIFIC AMERICAN, INC. EARLIEST COSMIC STRUCTURE mmostost likely took the form of a network of filaments. The first protogalaxies, small-scale systems about 30 to 100 light-years across, coalesced at the nodes of this network. Inside the protogalaxies, the denser regions of gas collapsed to form the first stars (inset). COPYRIGHT 2004 SCIENTIFIC AMERICAN, INC. After decades of study, researchers The Dark Ages to longer wavelengths and the universe have recently made great strides toward THE STUDY of the early universe is grew increasingly cold and dark. As- answering this question. Using sophisti- hampered by a lack of direct observa- tronomers have no observations of this cated computer simulation techniques, tions.