Browsing by Subject "astronomy"

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Astronomy: Selected Reference Sources for Instruction and Research
(1979) Sandy, John H.
Book Review of Extragalactic adventure: Our strange Universe, by Jean Heidmann
(Library Journal, 1982-04-15) Sandy, John H.
Convection in white dwarf stars
(2013) Luecke, Kevin J.P.; Montgomery, Mike
White dwarfs are some of the simplest stars. Because of their simplicity, they can be studied to learn fundamental facts about the universe. By studying them, we can learn about their progenitors, and 97% of stars end their lives a white dwarfs. These determinations, however, rely on the accuracy of our models of white dwarfs. In white dwarf science and the field of Astrophysics in general, one of the most prevalent, and least understood phenomena is convection. This paper discusses techniques for modeling convection in white dwarf stars, in particular, through an extension of the program Lcfit Theta, which attempts to find the size of convection zones. Most white dwarfs pulsate or oscillates in temperature and density during their life cycles. The oscillations can be seen from earth telescopes which record a star’s brightness as a function of time in a graph known as a ’light-curve’. These light-curves can be reproduced fairly well by a simple linear sum of sine functions corresponding to the frequencies and amplitudes at which it the star is oscillating. However, in stars where a convection zone is present at the surface, non-linear combinations of these sine functions appear in the light-curve. Lcfit Theta uses a model of these white dwarfs proposed by Montgomery which includes the effects of these convective regions, to generate synthetic light curves. By comparing these synthetic light curves to the measured stellar data, we can find the input parameters to Mongomery’s model which create a synthetic light curve that matches the data. By increasing the speed of this program dramatically, it is now possible to more fully probe the parameter space of these input parameters, especially the l and m values of the stellar modes of oscillation.
Earth's Cousin Found
(The Texas Scientist, 2016) The Texas Scientist
Emulating Stars
(The Texas Scientist, 2018) The Texas Scientist
Exoplanet A.I.
(The Texas Scientist, 2020) The Texas Scientist
First Science Results from SOFIA/FORCAST: Super-Resolution Imaging of the S140 Cluster at 37 Mu M
(2012-04) Harvey, Paul M.; Adams, Joseph D.; Herter, Terry L.; Gull, George; Schoenwald, Justin; Keller, Luke D.; De Buizer, James M.; Vacca, William; Reach, William; Becklin, E. E.; Harvey, Paul M.
We present 37 mu m imaging of the S140 complex of infrared sources centered on IRS1 made with the FORCAST camera on SOFIA. These observations are the longest wavelength imaging to resolve clearly the three main sources seen at shorter wavelengths, IRS 1, 2, and 3, and are nearly at the diffraction limit of the 2.5 m telescope. We also obtained a small number of images at 11 and 31 mu m that are useful for flux measurement. Our images cover the area of several strong submillimeter sources seen in the area-SMM 1, 2, and 3-that are not coincident with any mid-infrared sources and are not visible in our longer wavelength imaging either. Our new observations confirm previous estimates of the relative dust optical depth and source luminosity for the components in this likely cluster of early B stars. We also investigate the use of super-resolution to go beyond the basic diffraction limit in imaging on SOFIA and find that the van Cittert algorithm, together with the "multi-resolution" technique, provides excellent results.
Giant Magellan Telescope
(The Texas Scientist, 2015) The Texas Scientist
Hunting Dark Energy
(The Texas Scientist, 2021) The Texas Scientist
Into the Obscure Universe
(The Texas Scientist, 2019) The Texas Scientist
Light curve fitting on heterogeneous computers
(2013) Luecke, Kevin J.P.; Fussell, Donald
The field of computer science is one of the most recently created and rapidly expanding sciences. In the years since its inception in the mid 1900s, it has revolutionized the other sciences, businesses, and our personal lives. With increasing capabilities, however, comes increasing complexity. In order to deal with this complexity, computer scientists are creating new unconventional hardware which is becoming more and more parallel. With different hardware on your computer it becomes harder to effectively use all this computational power. GAMA (GPU And Multi-core Aware) addresses this problem by providing a runtime system that determines the amount of work that should be sent to each available resource dynamically. In order to demonstrate the abilities of this approach, a sample program with real applications in astrophysics has been implemented. This program, Lcfit Theta, attempts to find the size of convection zones in white dwarf stars. Most white dwarfs pulsate or oscillates in temperature and density during their life cycles. The oscillations can be seen from earth telescopes which record a star’s brightness as a function of time in a graph known as a ’light-curve’. These light-curves can be reproduced fairly well by a simple linear sum of sine functions corresponding to the frequencies and amplitudes at which it the star is oscillating. However, in stars where a convection zone is present at the surface, non-linear combinations of these sine functions appear in the light-curve. Lcfit Theta uses a model of these white dwarfs proposed by Montgomery which includes the effects of these convective regions, to generate synthetic light curves (9). By comparing these synthetic light curves to the measured stellar data, we can find the input parameters to Mongomery’s model which create a synthetic light curve that matches the data. One of these ’fitted’ input parameters is the size of the convection zone. This application is the focus of this thesis.
Observations Of Type Ia Supernova 2014J With Flitecam On SOFIA
(2015-05) Vacca, W. D.; Hamilton, R. T.; Savage, M.; Shenoy, S.; Becklin, E. E.; McLean, I. S.; Logsdon, S. E.; Marion, G. H.; Ashok, N. M.; Banerjee, D. P. K.; Evans, A.; Fox, O. D.; Garnavich, Peter; Gehrz, R. D.; Greenhouse, M.; Helton, L. A.; Kirshner, Robert P.; Shenoy, D.; Smith, N.; Spyromilio, J.; Starrfield, S.; Wooden, D. H.; Woodward, C. E.; Marion, G. H.
We present medium-resolution near-infrared (NIR) spectra, covering 1.1-3.4 mu m, of the normal Type Ia supernova (SN Ia) SN 2014J in M82 obtained with the FLITECAM instrument on board Stratospheric Observatory for Infrared Astronomy (SOFIA) between 17 and 26 days after maximum B light. Our 2.8-3.4 mu m spectra may be the first similar to 3 mu m spectra of an SN Ia ever published. The spectra spanning the 1.5-2.7 mu m range are characterized by a strong emission feature at similar to 1.77 mu m with a FWHM of similar to 11,000-13,000 kms(-1). We compare the observed FLITECAM spectra to the recent non-LTE delayed detonation models of Dessart et al. and find that the models agree with the spectra remarkably well in the 1.5-2.7 mu m wavelength range. Based on this comparison we identify the similar to 1.77 mu m emission peak as a blend of permitted lines of Co II. Other features seen in the 2.0-2.5 mu m spectra are also identified as emission from permitted transitions of Co II. However, the models are not as successful at reproducing the spectra in the 1.1-1.4 mu m range or between 2.8 and 3.4 mu m. These observations demonstrate the promise of SOFIA, which allows access to wavelength regions inaccessible from the ground, and serve to draw attention to the usefulness of the regions between the standard ground-based NIR passbands for constraining SN models.
Presentation: The Amazing Mission to Pluto: Three Billion Miles Away and We Made It!
(Environmental Science Institute, 2016-09-16) Stern, Alan; Environmental Science Institute
Publications by Members of the Faculty of The University of Texas
(University of Texas at Austin, 1944-08-04) The University of Texas
Publications by Members of the Faculty of The University of Texas
(University of Texas at Austin, 1945-08-15) Brogan, A.P.
Publications by Members of the Faculty of The University of Texas
(University of Texas at Austin, 1939) Brogan, A.P.
Publications by Members of the Faculty of The University of Texas
(University of Texas at Austin, 1943-08-16) The University of Texas
Publications by Members of the Faculty of The University of Texas
(University of Texas at Austin, 1941-12-01) The University of Texas
Quasar Answers
(The Texas Scientist, 2017) The Texas Scientist
Research + Pizza - Dr. Don Winget
(2013-04-02) Winget, Don
Harlan J. Smith Centennial Professor in Astronomy Dr. Don Winget discussed his work with researchers at Sandia National Laboratories replicating white dwarf stars in the middle of the New Mexico desert. Winget is using the world's largest x-ray generator in ways that are moving astronomy from a strictly observational field to an experimental one.