Astrophysics and Astronomy Commons^™

Limb Darkening And Planetary Transits: Testing Center-To-Limb Intensity Variations And Limb-Darkening Directly From Model Stellar Atmospheres, Hilding R. Neilson, Joseph T. Mcneil, Richard Ignace, John B. Lester

ETSU Faculty Works

The transit method, employed by Microvariability and Oscillation of Stars (MOST), Kepler, and various ground-based surveys has enabled the characterization of extrasolar planets to unprecedented precision. These results are precise enough to begin to measure planet atmosphere composition, planetary oblateness, starspots, and other phenomena at the level of a few hundred parts per million. However, these results depend on our understanding of stellar limb darkening, that is, the intensity distribution across the stellar disk that is sequentially blocked as the planet transits. Typically, stellar limb darkening is assumed to be a simple parameterization with two coefficients that are derived …

Entanglement Entropy With Background Gauge Fields, Bom Soo Kim

Physics and Astronomy Faculty Publications

We study the entanglement entropy, the Rényi entropy, and the mutual (Rényi) information of Dirac fermions on a 2 dimensional torus in the presence of constant gauge fields. We derive their general formulas using the equivalence between twisted boundary conditions and the background gauge fields. Novel and interesting physical consequences have been presented in arXiv:1705.01859. Here we provide detailed computations of the entropies and mutual information in a low temperature limit, a large radius limit, and a high temperature limit. The high temperature limit reveals rather different physical properties compared to those of the low temperature one: there exist …

Energy Dependence Of J/Ψ Production In Au + Au Collisions At √SNn = 39, 62.4 And 200 Gev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The inclusive J/ψ transverse momentum spectra and nuclear modification factors are reported at midrapidity (|y| < 1.0) in Au + Au collisions at √s_NN = 39, 62.4 and 200 GeV taken by the STAR experiment. A suppression of J/ψ production, with respect to the production in p + p scaled by the number of binary nucleon–nucleon collisions, is observed in central Au + Au collisions at these three energies. No significant energy dependence of nuclear modification factors is found within uncertainties. The measured nuclear modification factors can be described by model calculations that take into account both suppression of direct J/ψ production due to …

On The Binary Nature Of Massive Blue Hypergiants: High-Resolution X-Ray Spectroscopy Suggests That Cyg Ob2 12 Is A Colliding Wind Binary - Iopscience, Lidia M. Oskinova, David P. Huenemoerder, Wolf-Rainer Hamann, Tomer Shenar, A. A.C. Sander, Richard Ignace, H. Todt, R. Hainich

ETSU Faculty Works

The blue hypergiant Cyg OB2 12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xivand Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere …

Stellar Stream Candidates In The Solar Neighborhood Found In The Lamost Dr3 And Tgas, X. L. Liang, Terry Oswalt, J. K. Zhao, Y. Q. Chen, G. Zhao

Publications

We have cross-matched the LAMOST DR3 with the Gaia DR1 TGAS cata- logs and obtained a sample of 166,827 stars with reliable kinematics. A technique based on the wavelet transform was applied to detect significant overdensities in velocity space among five subsamples divided by spatial position. In total, 16 sig- nificant overdensities of stars with very similar kinematics were identified. Among these, four are new stream candidates and the rest are previously known groups. Both the U-V velocity and metallicity distributions of the local sample show a clear gap between the Hercules structure and the Hyades-Pleiades structure. The U-V positions …

The Sdss-Iv Manga Sample: Design, Optimization, And Usage Considerations, David A. Wake, Kevin Bundy, Aleksandar M. Diamond-Stanic, Renbin Yan, Michael R. Blanton, Matthew A. Bershady, José R. Sánchez-Gallego, Niv Drory, Amy Jones, Guinevere Kauffmann, David R. Law, Cheng Li, Nicholas Macdonald, Karen Masters, Daniel Thomas, Jeremy Tinker, Anne-Marie Weijmans, Joel R. Brownstein

Physics and Astronomy Faculty Publications

We describe the sample design for the SDSS-IV MaNGA survey and present the final properties of the main samples along with important considerations for using these samples for science. Our target selection criteria were developed while simultaneously optimizing the size distribution of the MaNGA integral field units (IFUs), the IFU allocation strategy, and the target density to produce a survey defined in terms of maximizing signal-to-noise ratio, spatial resolution, and sample size. Our selection strategy makes use of redshift limits that only depend on i-band absolute magnitude (M_i ), or, for a small subset of our sample, …

An Ultrahot Gas-Giant Exoplanet With A Stratosphere, Thomas M. Evans, David K. Sing, Tiffany Kataria, Jayesh M. Goyal, Nikolay Nikolov, Hannah R. Wakeford, Drake Deming, Mark S. Marley, David S. Amundsen, Gilda E. Ballester, Joanna K. Barstow, Lofti Ben-Jaffel, Vincent Bourrier, Lars A. Buchhave, Ofer Cohen, David Ehrenreich, Antonio García Muñoz, Gregory W. Henry, Heather Knutson, Panayotis Lavvas, Alain Lecavelier Des Etangs, Nikole K. Lewis, Mercedes López-Morales, Avi M. Mandell, Jorge Sanz-Forcada, Pascal Tremblin, Roxana Lupu

Information Systems and Engineering Management Research Publications

Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere—where temperature increases with altitude—these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the …

A Vision For Canadian Space Exploration, Ilaria Caiazzo, Sarah C. Gallagher, Jeremy Heyl

Physics and Astronomy Publications

We propose a sustained and balanced program in space exploration to fuel innovation in the space sector, support Canada's world-leading space researchers, inspire the next generation of scientists and innovators, and create thousands of highly skilled, well-paying jobs for Canadians. During the next decade we recommend a total investment of approximately $1B, increasing to $1.3B in each decade that follows, including a regular flagship mission that Canada would lead and a constellation of smaller missions, either led by Canada or in collaboration with international partners.

Evaluation Of Radiation And Design Criteria For A Lunar Habitat, Hayley E. Bower, Daniel Gomez, Antonio Bobet, Julio A. Ramirez, Shirley J. Dyke, H. Jay Melosh

The Summer Undergraduate Research Fellowship (SURF) Symposium

Extraterrestrial habitation has long been the object of science fiction, and experts in the fields of science and engineering have proposed many designs for a lunar base. The research conducted has focused on either structural stability, radiation protection, or meteorite-impact vulnerabilities, but rarely have these been considered together. The Resilient ExtraTerrestrial Habitats (RETH) project aims to design a lunar habitat from a hazards perspective, considering general degradation, meteorite impacts, seismic activity, radiation exposure, thermal extremes, and geomagnetic storms in addition to the physiological, psychological, and sociological aspects of astronauts living in such a habitat. Several members of the RETH team …

Magnetospherically-Trapped Dust And A Possible Model For The Unusual Transits At Wd1145+017, J. Farihi, Ted Von Hippel, J. E. Pringle

Publications

The rapidly evolving dust and gas extinction observed towardsWD1145+017 has opened a real-time window onto the mechanisms for destruction-accretion of planetary bodies onto white dwarf stars, and has served to underline the importance of considering the dynamics of dust particles around such objects. Here it is argued that the interaction between (charged) dust grains and the stellar magnetic field is an important ingredient in understanding the physical distribution of infrared emitting particles in the vicinity of such white dwarfs. These ideas are used to suggest a possible model for WD 1145+017 in which the unusual transit shapes are caused by …

Stellar Stream Candidates In The Solar Neighborhood Found In The Lamost Dr3 And Tgas, X. L. Liang, J. K. Zhao, T. D. Oswalt, Y. Q. Chen, L. Zhang, G. Zhao

Publications

We have cross-matched the LAMOST DR3 with the Gaia DR1 TGAS catalogs and obtained a sample of 166,827 stars with reliable kinematics. A technique based on the wavelet transform was applied to detect significant overdensities in velocity space among five subsamples divided by spatial position. In total, 16 significant overdensities of stars with very similar kinematics were identified. Among these, four are new stream candidates and the rest are previously known groups. Both the U–V velocity and metallicity distributions of the local sample show a clear gap between the Hercules structure and the Hyades–Pleiades structure. The U– …

A Bright Short Period M-M Eclipsing Binary From The Kelt Survey: Magnetic Activity And The Mass–Radius Relationship For M Dwarfs, J. B. Lubin, J. E. Rodriguez, G. Zhou, K. E. Conroy, K. G. Stassun, K. Collins, D. J. Stevens, J. Labadie-Bartz, C. Stockdale, G. Myers, K. D. Colón, J. Bento, P. Kehusmaa, R. Petrucci, E. Jofré, S. N. Quinn, M. B. Lund, R. B. Kuhn, R. J. Siverd, T. G. Beatty, C. Harlingten, J. Pepper, B. S. Gaudi, D. James, Eric L.N. Jensen, D. Reichart, L. Kedziora-Chudczer, J. Bailey, G. Melville

Physics & Astronomy Faculty Works

We report the discovery of KELT J041621-620046, a moderately bright (J ~ 10.2) M-dwarf eclipsing binary system at a distance of 39 ± 3 pc. KELT J041621-620046 was first identified as an eclipsing binary using observations from the Kilodegree Extremely Little Telescope (KELT) survey. The system has a short orbital period of ~1.11 days and consists of components with and in nearly circular orbits. The radii of the two stars are and . Full system and orbital properties were determined (to ∼10% error) by conducting an EBOP (Eclipsing Binary Orbit Program) global modeling of the high precision photometric and spectroscopic …

Detection Of A Substantial Molecular Gas Reservoir In A Brightest Cluster Galaxy At Z = 1.7, Tracy M.A. Webb, James Lowenthal, Min Yun, Allison G. Nobel, Adam Muzzin, Gillian Wilson, H.K.C. Yee, Ryan Cybulski, D. H. Hughes

Astronomy: Faculty Publications

We report the detection of CO(2–1) emission coincident with the brightest cluster galaxy (BCG) of the high- redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091 ± 0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well fit by a single-component Gaussian with an RSR-resolution-corrected FWHM of 569 ± 63kms−1. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen …

Accelerator Based Fusion Reactor, Keh-Fei Liu, Alexander Wu Chao

Physics and Astronomy Faculty Publications

A feasibility study of fusion reactors based on accelerators is carried out. We consider a novel scheme where a beam from the accelerator hits the target plasma on the resonance of the fusion reaction and establish characteristic criteria for a workable reactor. We consider the reactions d+t→n+α, d+³H_e→p+α and p+¹¹B→3α in this study. The critical temperature of the plasma is determined from overcoming the stopping power of the beam with the fusion energy gain. The needed plasma lifetime is determined …

An Upper Limit On The Tightening Of Galactic Spiral Arm Pitch Angle In Cosmic Time, Douglas William Shields

Graduate Theses and Dissertations

We present Spirality, a novel method of measuring pitch angle by fitting galaxy images to spiral templates of known pitch. Using this algorithm in concert with 2-dimensional Fast Fourier Transform (2DFFT), we determined that the pitch angle of the redshift 2.011 galaxy GZ5001 (J2000 RA 189.14811 degrees, Dec 62.24002 degrees) is approximately (16.2 +/- 2.6) degrees. The redshift 2.3219 galaxy GS21 (J2000 RA 53.14863 degrees, Dec -27.95469 degrees), which is believed to be the most distant galaxy with visible spiral structure yet measured, has a pitch of approximately (-10.6 +/- 1.6) degrees. Using a large sample of galaxies from the …

Erratum: "The Sluggs Survey: A Catalog Of Globular Cluster Radial Velocities" (2017, Aj, 153, 114), Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky, Jay Strader, Caroline Foster, Christopher Usher, Lee Spitler, Sabine Bellstedt, Nicola Pastorello, Sreeja Kartha, Zach Jennings, Alexa Villaume, Asher Wasserman, Vincenzo Pota

Faculty Publications

This is an erratum for the article 2017 AJ 153 114.

Growth And Survivability Of Microorganisms At Martian Temperatures And Pressures, Rebecca Lynne Mickol

Graduate Theses and Dissertations

The discovery of methane in the martian atmosphere via numerous ground- and space-based sources has prompted the study of methanogens as models for life on Mars. Methanogens are microorganisms within the domain Archaea, many of which utilize carbon dioxide (CO2) and hydrogen to produce methane. The non-photosynthetic nature of methanogens indicates that they could exist in sub-surface environments, protected from harmful UV and ionizing radiation on the surface of Mars. These organisms also do not require organics, which are sparse on the planet.

Additionally, the wide variety of environments we find life in on Earth, as well as evidence for …

Understanding Progenitors Of Gamma Ray Bursts With Multi-Wavelength Properties, Ye Li

UNLV Theses, Dissertations, Professional Papers, and Capstones

Gamma-ray bursts (GRBs) are among the most brilliant explosions in the universe, named for their intense, seconds-duration $\gamma$-ray emission. They are generally classified into two categories according to the durations of their $\gamma$-ray emission: the long-duration GRBs (LGRBs) with durations more than 2 seconds, and the short-duration GRBs (SGRBs) with durations less than 2 seconds. Most SGRBs are believed to originate from mergers of compact stars (e.g., neutron star-neutron star and neutron star-black hole; also known as Type I GRBs by their physical mechanism), while the LGRBs are thought to originate from core-collapse of massive stars (Type II). In addition …

Secular Resonances During Main-Sequence And Post-Main-Sequence Planetary System Dynamics, Jeremy L. Smallwood

UNLV Theses, Dissertations, Professional Papers, and Capstones

We investigate gravitational perturbations of an asteroid belt by secular resonances. We ap- ply analytic and numerical models to main–sequence and post–main–sequence planetary systems. First, we investigate how the asteroid impact rate on the Earth is affected by the architecture of the planetary system. We find that the nu6 resonance plays an important role in the asteroid collision rate with the Earth. Compared to exoplanetary systems, the solar system is somewhat special in its lack of a super–Earth mass planet in the inner solar system. We therefore consider the effects of the presence of a super–Earth in the terrestrial planet …

The Formation And Dynamics Of Clouds In The Environment Of Active Galactic Nuclei, Timothy Waters

UNLV Theses, Dissertations, Professional Papers, and Capstones

Active galactic nuclei (AGN) are among the most luminous objects in the universe and are known to be powered by accretion onto supermassive black holes in the centers of galaxies. AGN clouds are prominent components of successful models that attempt to unify the diversity of AGN. These clouds are often hypothesized to be the source of the broad and narrow line emission features seen in AGN spectra. Moreover, the high column densities of gas needed to account for broad absorption lines has been attributed to the same population of clouds, while the motion of AGN clouds has been invoked to …