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Abstracts of the 234Th AAS Meeting (St Abstracts of the 234th AAS Meeting (St. Louis, MO) American Astronomical Society June, 2019 101 — Kavli Foundation Lecture: during the perihelion passage of sungrazing comet C/2012 S1 (ISON) in November 2013 are presented Key Outstanding Questions in and compared with earlier measurements made Galaxy Formation and How to of Kreutz sungrazing comet C/2011 W3 (Lovejoy). Comet ISON was an Oort Cloud object, probably Answer Them, Alice Shapley entering the solar system for the first time. Strong (UCLA) evidence was found for a radical change in the polarization properties once the tail particles ap- 101.01 — Key Outstanding Questions in Galaxy proached within 10 solar radii of Sun center. Above Formation and How to Answer Them this apparent threshold, the polarization properties of Comet ISON appeared very similar to those seen Alice E. Shapley1 previously for Comet Lovejoy, with high positive 1 UCLA (Los Angeles, California, United States) polarization, and a broad negative branch reaching out to an inversion point between 40-50 degrees. Understanding the formation and evolution of galax- Below 10 solar radii the polarization levels drop ies remains one of the great challenges of mod- dramatically; an effect not seen for Comet Lovejoy. ern cosmology. Key outstanding questions include: We conclude that radiation processes close to the What are the physical processes driving the forma- Sun, and possibly starting as far out as 0.25 AU, are tion of stars in individual galaxies? How do galaxies responsible for the high levels of polarizations seen exchange matter and energy with their intergalac- in both comets, and that the sublimation of olivines tic environments? How do the impressive variety and pyroxenes is responsible for the precipitous of galactic structures that we observe today assem- drop in Comet ISON’s polarization below 10 solar ble? How do supermassive black holes affect the radii. evolution of their host galaxies? And how do large- scale structures of galaxies assemble across cosmic 102.02 — Earth At Mars time? I will address these important questions in galaxy formation using new results from powerful Michael L. Cobb1; Samantha Hasler1 ground-based and space-based facilities. I will also 1 Southeast Missouri State Univ. (Cape Girardeau, Missouri, look ahead to future progress with upcoming facili- United States) ties. With its current chemical makeup, Earth would freeze solid if placed at Mars’ orbit. This research 102 — The Solar System Poster explores the possibility of an Earth like planet main- Session taining liquid water in an orbit like Mars. We used the Global Circulation Model software (Mod- 102.01 — Changing linear polarization properties elE) provided by the Goddard Institute for Space in the dust tail of comet C/2012 S1 (ISON) Studies to reposition Earth into the orbit of Mars. We then increase the amount of greenhouse gasses, pri- 2,1 William T. Thompson marily CO2 , in the atmosphere in an attempt to keep 1 NASA/GSFC (Greenbelt, Maryland, United States) parts of the planet from freezing solid. 2 ADNET Systems, Inc (Lanham, Maryland, United States) Polarization measurements made with the STEREO/SECCHI COR1 and COR2 coronagraphs 1 102.03 — Carbonyl sulfide (OCS): Detection in two 2 UC Berkeley (Berkeley, California, United States) Oort cloud comets and upper-limits in two Jupiter-family comets. We establish one step along a technical route to achieving cm/s scale accuracy for astronomical spec- 1 1,2 1 Mohammad Saki ; Erika L. Gibb ; Nathan Roth ; trographs over long time scales, which is critical for 2 3 Michael A. DiSanti ; Neil Dello Russo ; Ronald the characterization of earth sized exoplanets and 3 4 Vervack ; Hideyo Kawakita measurement of cosmic redshift drift over years. Us- 1 University of Missouri St. Louis (Saint Louis, Missouri, United ing a new method called “crossfading” for exter- States) nally dispersed interferometers (EDI) to get highly 2 Goddard Center for Astrobiology, NASA GSFC (Greenbelt, Mary- robust spectra, we have recently demonstrated a fac- land, United States) tor of 1000x reduction in the net shift of an EDI mea- 3 Johns Hopkings University, Applied Physics Lab (Laurel, Mary- sured ThAr line to a deliberate simulated wavelength land, United States) translation of the detector. This 1000x gain in dis- 4 Division of Science, Kyoto Sangyo University (Kyoto, Japan) perser stability can be combined with conventional stability gains afforded by fiber scramblers, vacuum Comets are thought to retain volatiles from the time tanks, and thermal control, to provide an additional of their formation; therefore, characterizing their 2 to 3 orders of magnitude reduction in the net PSF composition should provide insights into the con- shift drift. Crossfading combines high and low delay ditions present in the early solar system. Chemi- process signals using strategic weightings to cancel cal diversity has been noted among comets based on the net reaction to a wavelength drift of the detec- measurements at all wavelengths, including near-IR tor. This can be applied by deploying interferome- studies of parent volatiles. Of these molecules, OCS ters having a stepped mirror that produces two si- is particularly underrepresented in parent volatile multaneous delays, or can be applied to a single de- studies, having been targeted in only a small subset lay that overlaps the spectral response of the ordi- of comets (four OCCs so far). Newer instruments, nary spectrum, and for that case all time scale drifts such as the high-resolution, near-infrared iSHELL are mitigated. Crossfading also mitigates increases spectrograph at the NASA-IRTF on Maunakea, HI, in PSF width and asymmetric distortions. with its large spectral grasp and active M-band guid- ing capabilities, now enable routine sampling of OCS 103.02 — Characterization of Teledyne emissions near 4.9 μm along with other molecules, HAWAII-4RG-15 Infrared Detector Arrays thus we will be able to begin establishing statistics for the OCS content of comets. We targeted OCS in Klaus W. Hodapp1; Donald Hall1; Shane Jacobson1; comets 46P/Wirtanen, 21P/Giacobini–Zinner, and Mickie Hirata2; Markus Loose3; Majid Zandian4 C/2015 ER61 in 2017-2018 using iSHELL, as well as 1 Univ. of Hawaii (Hilo, Hawaii, United States) in C/2002 T7 (LINEAR) using CSHELL in 2004. We 2 Washington University in St. Louis (St. Louis, Missouri, United will present production rates and mixing ratios (with States) 3 respect to H2O) of OCS for these comets and will Markury Scientific (Thousand Oaks, California, United States) place our results in the context of comets measured 4 Teledyne Imaging Sensors (Camarillo, California, United States) to date. This work was supported by the NASA Earth and Space Science Fellowship, Solar System Work- With funding from NSF, the University of Hawaii In- ings, Solar System Observations, and Astrobiology stitute for Astronomy, in partnership with Teledyne Programs, and NSF Solar and Planetary Research Imaging Sensors, LLC, have, over the past decade, Grants. developed the HAWAII-4RG-15 near infrared detec- tor arrays with a cut-off wavelength of 2.5 micro- meters. The ”R” in the name indicates the presence 103 — Instrumentation: Ground of reference pixels, the ”G” stands for guide-window Based or Airborne & Computation mode, and the ”15” indicates the pixel size in micro- meters. These devices are usually abbreviated as Poster Session H4RG-15. The H4RG-15 detector arrays can operate with up 103.01 — A 1000x Stabler Spectrograph using an to 64 output amplifiers, but in our testing program, Interferometer with Crossfaded Delays they were operated by a single Teledyne SIDECAR ASIC with 32 signal channels. In addition to the David John Erskine1; Eric Linder2 frame of 4 rows and columns of reference pixels that 1 LLNL (Livermore, California, United States) 2 the older H2RG devices are using, the H4RG-15 pro- be implemented at both telescopes. Using materials vides reference pixels that can be read out inter- and resources available in the Astronomical Instru- leaved with the IR-sensitive science pixels. In our mentation Laboratory at Southern Connecticut State testing, we routinely used the interleaved reference University, an optical system has been developed to pixels, leading to a full-frame read-out time of 5.4 s. work toward this goal but outfitting the first tele- As part of the development program, Teledyne scope in this way. The light from the telescope is col- had produced three near-science-grade detector ar- limated and directed toward a reflective diffraction rays with two different passivation processes. One of grating. This is then re-imaged using a second lens these, referred to as PV1 here, turned out to be clearly and directed onto the pixels of the photon detector. superior with respect to persistence effects. These optical components have been placed inside an The telescope tests of the best (PV1) device were aluminum housing and can be mounted to the tele- done using the ULB-Cam test system restricted to the scope for test observations. A status report will be J and H bands. These tests showed that under con- given on the observations so far. If this can be repli- ditions of low electronic pickup noise, the use of the cated at the other telescope, the signal-to-noise ratio interleaved reference pixels does not offer an advan- achievable with the instrument could be improved tage over the use of the frame reference pixels. Most by a factor of 2.8. importantly, the telescope tests with standard dither- ing data acquisition showed no noticeable detector 103.04 — The Next Generation GBT persistence in the broad J and H filters. 1 1 The laboratory tests showed only minimal, short Natalie Butterfield ; William P. Armentrout ; Amber 1 1 1 duration persistence on the PV1 device, and moder- Bonsall ; David T. Frayer ; Frank D. Ghigo ; Tapasi 1 1 1 ate persistence on the PV2 devices.
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