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Articles 31 - 60 of 203
Full-Text Articles in Astrophysics and Astronomy
Sloan Digital Sky Survey Iv: Mapping The Milky Way, Nearby Galaxies, And The Distant Universe, Michael R. Blanton, Matthew A. Bershady, Bela Abolfathi, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Javier Alonso-García, Friedrich Anders, Scott F. Anderson, Brett Andrews, Erik Aquino-Ortíz, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Kathleen A. Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Dominic Bates, Falk Baumgarten, Julian Bautista, Rachael Beaton, Francesco Belfiore, Chad F. Bender, Andreas A. Berlind, Mariangela Bernardi, Florian Beutler, Renbin Yan, Daniel Lazarz, Kai Zhang
Sloan Digital Sky Survey Iv: Mapping The Milky Way, Nearby Galaxies, And The Distant Universe, Michael R. Blanton, Matthew A. Bershady, Bela Abolfathi, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Javier Alonso-García, Friedrich Anders, Scott F. Anderson, Brett Andrews, Erik Aquino-Ortíz, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Kathleen A. Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Dominic Bates, Falk Baumgarten, Julian Bautista, Rachael Beaton, Francesco Belfiore, Chad F. Bender, Andreas A. Berlind, Mariangela Bernardi, Florian Beutler, Renbin Yan, Daniel Lazarz, Kai Zhang
Physics and Astronomy Faculty Publications
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z ~ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z ~ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, …
Retrieval Of Atmospheric Properties Of Cloudy L Dwarfs, Ben Burningham, M. S. Marley, M. R. Line, R. Lupu, Channon Visscher, C. V. Morley, D. Saumon, R. Freedman
Retrieval Of Atmospheric Properties Of Cloudy L Dwarfs, Ben Burningham, M. S. Marley, M. R. Line, R. Lupu, Channon Visscher, C. V. Morley, D. Saumon, R. Freedman
Faculty Work Comprehensive List
We present the first results from applying the spectral inversion technique in the cloudy L dwarf regime. Our new framework provides a flexible approach to modelling cloud opacity which can be built incrementally as the data require and improves upon previous retrieval experiments in the brown dwarf regime by allowing for scattering in two-stream radiative transfer. Our first application of the tool to two mid-L dwarfs is able to reproduce their near-infrared spectra far more closely than grid models. Our retrieved thermal, chemical and cloud profiles allow us to estimate Teff=1796−25+23" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; …
The Acs Survey Of Galactic Globular Clusters Xiv: Bayesian Single-Population Analysis Of 69 Globular Clusters, R. Wagner-Kaiser, Ted Von Hippel, A. Sarajedini, D. C. Stenning, D. A. Van Dyck, Et Al.
The Acs Survey Of Galactic Globular Clusters Xiv: Bayesian Single-Population Analysis Of 69 Globular Clusters, R. Wagner-Kaiser, Ted Von Hippel, A. Sarajedini, D. C. Stenning, D. A. Van Dyck, Et Al.
Publications
We use Hubble Space Telescope (HST) imaging from the ACS Treasury Survey to determine fits for single population isochrones of 69 Galactic globular clusters. Using robust Bayesian analysis techniques, we simultaneously determine ages, distances, absorptions, and helium values for each cluster under the scenario of a \single" stellar population on model grids with solar ratio heavy element abundances. The set of cluster parameters is determined in a consistent and reproducible manner for all clusters using the Bayesian analysis suite BASE-9. Our results are used to re-visit the age-metallicity relation. We find correlations with helium and several other parameters such as …
The Ages Of The Thin Disk, Thick Disk, And The Halo From Nearby White Dwarfs, Mukremin Kilic, Ted Von Hippel, Jeffrey A. Munn, Hugh C. Harris, James W. Liebert, Et Al.
The Ages Of The Thin Disk, Thick Disk, And The Halo From Nearby White Dwarfs, Mukremin Kilic, Ted Von Hippel, Jeffrey A. Munn, Hugh C. Harris, James W. Liebert, Et Al.
Publications
We present a detailed analysis of the white dwarf luminosity functions derived from the local 40 pc sample and the deep proper motion catalog of Munn et al. (2014, 2017). Many of the previous studies ignored the contribution of thick disk white dwarfs to the Galactic disk luminosity function, which results in an erronous age measurement. We demonstrate that the ratio of thick/thin disk white dwarfs is roughly 20% in the local sample. Simultaneously fitting for both disk components, we derive ages of 6.8-7.0 Gyr for the thin disk and 8.7 ± 0.1 Gyr for the thick disk from the …
M Dwarf Planet Habitability, Ben Koenigs
M Dwarf Planet Habitability, Ben Koenigs
Gateway Prize for Excellent Writing
The habitability of M dwarf planets has been debated greatly, as their parent stars possess both beneficial and detrimental qualities for the development of life. Initially, the astrobiological community questioned their habitability (Dole 1964), but as research and modeling techniques have improved, astrobiologists have become more accepting of the idea of life on M dwarf planets (Shields et al. 2016). The question of these planets’ habitability has great significance, because their long lifespans and commonality in the universe make them legitimate candidates for a plethora of extrasolar spacecraft missions, and potentially for the first discovery of life in other systems.
Photometric Flux In Exonest, Steven Kwun Young
Photometric Flux In Exonest, Steven Kwun Young
Legacy Theses & Dissertations (2009 - 2024)
As a planet orbits its parent star, the amount of light that reaches Earth from that system is dependent on the dynamics of that star system. Known as photometric variations, these slight changes in light flux are detectable by the Kepler Space Telescope and must be fully understood in order to properly model the system. There are four main factors that contribute to the photometric flux: reflected light from the planet, thermal emissions from the planet, doppler boosting in the light being emitted by the star, and ellipsoidal variations in the star. The total observed flux from each contribution then …
Very High Energy Observations Of The Binaries V 404 Cyg And 4u 0115+634 During Giant X-Ray Outbursts, P. T. Reynolds, Et Al
Very High Energy Observations Of The Binaries V 404 Cyg And 4u 0115+634 During Giant X-Ray Outbursts, P. T. Reynolds, Et Al
Physical Sciences Publications
Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as 107. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in 2015 June and October, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hr of observations of the microquasar V 404 Cyg from 2015, June 20–21. The upper flux limits …
Hubble's Law Implies Benford's Law For Distances To Galaxies, Theodore P. Hill, Ronald F. Fox
Hubble's Law Implies Benford's Law For Distances To Galaxies, Theodore P. Hill, Ronald F. Fox
Research Scholars in Residence
A recent article by Alexopoulos and Leontsinis presented empirical evidence that the first digits of the distances from the Earth to galaxies are a reasonably good fit to the probabilities predicted by Benford’s law, the well known logarithmic statistical distribution of significant digits. The purpose of the present article is to give a theoretical explanation, based on Hubble’s law and mathematical properties of Benford’s law, why galaxy distances might be expected to follow Benford’s law. The new galaxy-distance law derived here, which is robust with respect to change of scale and base, to additive and multiplicative computational or observational errors, …
A Search For Brief Optical Flashes Associated With The Seti Target Kic 8462852, P. T. Reynolds, Et Al
A Search For Brief Optical Flashes Associated With The Seti Target Kic 8462852, P. T. Reynolds, Et Al
Physical Sciences Publications
The F-type star KIC 8462852 has recently been identified as an exceptional target for search for extraterrestrial intelligence (SETI) observations. We describe an analysis methodology for optical SETI, which we have used to analyze nine hours of serendipitous archival observations of KIC 8462852 made with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of pulsed optical beacons, above a pulse intensity at the Earth of approximately , is found. We also discuss the potential use of imaging atmospheric Cherenkov telescope arrays in searching for extremely short duration optical transients in general.
Leech Exoplanet Imaging Survey: Characterization Of The Coldest Directly Imaged Exoplanet, Gj 504 B, And Evidence For Super-Stellar Metallicity, Andrew J. Skemer, Caroline V. Morley, Neil T. Zimmerman, Michael F. Skrutskie, Jarron Leisenring, Esther Buenzli, Mickael Bonnefoy, Vanessa Bailey, Philip Hinz, Denis Defrere, Simone Esposito, Daniel Apai, Beth Biller, Wolfgang Brandner, Laird Close, Justin R. Crepp, Robert J. De Rosa, Silvano Desidera, Josh Eisner, Jonathan Fortney, Richard Freedman, Thomas Henning, Karl-Heinz Hofmann, Taisiya Kopytova, Roxana Lupu, Anne-Lise Maire, Jared R. Males, Mark Marley, Katie Morzinski, Apurva Oza, Jenny Patience, Abhijith Rajan, George Rieke, Dieter Schertl, Joshua Schlieder, Jordan Stone, Kate Su, Amali Vaz, Channon Visscher, Kimberly Ward-Duong, Gerd Weigelt, Charles E. Woodward
Leech Exoplanet Imaging Survey: Characterization Of The Coldest Directly Imaged Exoplanet, Gj 504 B, And Evidence For Super-Stellar Metallicity, Andrew J. Skemer, Caroline V. Morley, Neil T. Zimmerman, Michael F. Skrutskie, Jarron Leisenring, Esther Buenzli, Mickael Bonnefoy, Vanessa Bailey, Philip Hinz, Denis Defrere, Simone Esposito, Daniel Apai, Beth Biller, Wolfgang Brandner, Laird Close, Justin R. Crepp, Robert J. De Rosa, Silvano Desidera, Josh Eisner, Jonathan Fortney, Richard Freedman, Thomas Henning, Karl-Heinz Hofmann, Taisiya Kopytova, Roxana Lupu, Anne-Lise Maire, Jared R. Males, Mark Marley, Katie Morzinski, Apurva Oza, Jenny Patience, Abhijith Rajan, George Rieke, Dieter Schertl, Joshua Schlieder, Jordan Stone, Kate Su, Amali Vaz, Channon Visscher, Kimberly Ward-Duong, Gerd Weigelt, Charles E. Woodward
Faculty Work Comprehensive List
As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly-imaged exoplanets were all L-type. Recently, Kuzuhara et al. (2013) announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the …
Exceptionally Bright Tev Flares From The Binary Ls I+61 Degrees 303, P. T. Reynolds, Et Al
Exceptionally Bright Tev Flares From The Binary Ls I+61 Degrees 303, P. T. Reynolds, Et Al
Physical Sciences Publications
The TeV binary system LS I +61° 303 is known for its regular, non-thermal emission pattern that traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5% and 15% of the steady flux from the Crab Nebula (>300 GeV). In this article, VERITAS observations of LS I +61° 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. …
Ultraviolet Emission Lines Of Si Ii In Cool Star And Solar Spectra, Sibasish Laha, Francis P. Keenan, Gary J. Ferland, Catherine A. Ramsbottom, Kanti M. Aggarwal, Thomas R. Ayres, Marios Chatzikos, Peter A. M. Van Hoof, Robin J. R. Williams
Ultraviolet Emission Lines Of Si Ii In Cool Star And Solar Spectra, Sibasish Laha, Francis P. Keenan, Gary J. Ferland, Catherine A. Ramsbottom, Kanti M. Aggarwal, Thomas R. Ayres, Marios Chatzikos, Peter A. M. Van Hoof, Robin J. R. Williams
Physics and Astronomy Faculty Publications
Recent atomic physics calculations for Si ii are employed within the cloudy modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, β Geminorum, α Centauri A and B, as well as previously published HST/GHRS observations of α Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrograph. Discrepancies found previously between theory and observation for line intensity ratios involving the 3s23p 2PJ–3s3p2 4PJ' intercombination multiplet of Si II at ∼ 2335 Å are significantly reduced, as are those for …
Empirical Line Lists And Absorption Cross Sections For Methane At High Temperatures, R. J. Hargreaves, P. F. Bernath, J. Bailey, M. Dulick
Empirical Line Lists And Absorption Cross Sections For Methane At High Temperatures, R. J. Hargreaves, P. F. Bernath, J. Bailey, M. Dulick
Chemistry & Biochemistry Faculty Publications
Hot methane is found in many "cool" sub-stellar astronomical sources including brown dwarfs and exoplanets, as well as in combustion environments on Earth. We report on the first high-resolution laboratory absorption spectra of hot methane at temperatures up to 1200 K. Our observations are compared to the latest theoretical spectral predictions and recent brown dwarf spectra. The expectation that millions of weak absorption lines combine to form a continuum, not seen at room temperature, is confirmed. Our high-resolution transmittance spectra account for both the emission and absorption of methane at elevated temperatures. From these spectra, we obtain an empirical line …
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping
ETSU Faculty Works
We present an overview of four deep phase-constrained Chandra HETGS X-ray observations of δ Ori A. Delta Ori A is actually a triple system that includes the nearest massive eclipsing spectroscopic binary, δ Ori Aa, the only such object that can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, δ Ori Aa2, has a much lower X-ray luminosity than the brighter primary (δ Ori Aa1), δ Ori Aa provides a unique system with which to test the spatial distribution of the X-ray emitting gas around δ Ori Aa1 via occultation by the photosphere of, and …
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss
ETSU Faculty Works
We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system δ Ori A, consisting of a binary O9.5II+early-B(Aa1 and Aa2) with P=5.7 days, and a more distant tertiary(O9 IV P 400 years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV)curve of Aa1. While we are unable …
A Re-Interpretation Of The Triangulum-Andromeda Stellar Clouds: A Population Of Halo Stars Kicked Out Of The Galactic Disk, Adrian M. Price-Whelan, Kathryn V. Johnston, Allyson A. Sheffield, Chervin F. P. Laporte, Branimir Sesar
A Re-Interpretation Of The Triangulum-Andromeda Stellar Clouds: A Population Of Halo Stars Kicked Out Of The Galactic Disk, Adrian M. Price-Whelan, Kathryn V. Johnston, Allyson A. Sheffield, Chervin F. P. Laporte, Branimir Sesar
Publications and Research
The Triangulum–Andromeda stellar clouds (TriAnd1 and TriAnd2) are a pair of concentric ring- or shell-like overdensities at large R (≈30 kpc) and Z (≈−10 kpc) in the Galactic halo that are thought to have been formed from the accretion and disruption of a satellite galaxy. This paper critically reexamines this formation scenario by comparing the number ratio of RR Lyrae to M giant stars associated with the TriAnd clouds with other structures in the Galaxy. The current data suggest a stellar population for these overdensities (fRR: MG < 0.38 at 95 per cent confidence) quite unlike any of the known satellites of the Milky Way (fRR: MG ≈ 0.5 for the very largest and f …
Star Formation And Relaxation In 379 Nearby Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner
Star Formation And Relaxation In 379 Nearby Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner
Dartmouth Scholarship
We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes Mr < −19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 ± 0.003) is higher than that in all relaxed clusters (0.097 ± 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters.
Ultracool White Dwarfs And The Age Of The Galactic Disc, A. Gianninas, B. Curd, John R. Thorstensen, Mukremin Kilic
Ultracool White Dwarfs And The Age Of The Galactic Disc, A. Gianninas, B. Curd, John R. Thorstensen, Mukremin Kilic
Dartmouth Scholarship
We present parallax observations and a detailed model atmosphere analysis of 54 cool and ultracool (Teff < 4000 K) white dwarfs (WDs) in the solar neighbourhood. For the first time, a large number of cool and ultracool WDs have distance and tangential velocities measurements available. Our targets have distances ranging from 21 pc to >100 pc, and include five stars within 30 pc. Contrary to expectations, all but two of them have tangential velocities smaller than 150 km s−1 thus suggesting Galactic disc membership. The oldest WDs in this sample have WD cooling ages of 10 Gyr, providing a firm lower limit to the age of the thick disc population. Many of our targets have uncharacteristically large radii, indicating that they are low mass WDs. It appears that we have detected the brighter population of cool and ultracool …
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
ETSU Faculty Works
Massive star winds are complex radiation-hydrodynamic (sometimes magnetohydrodynamic) outflows that are propelled by their enormously strong luminosities. The winds are often found to be structured and variable, but can also display periodic or quasi-periodic behavior in a variety of wind diagnostics. The regular variations observed in putatively single stars, especially in UV wind lines, have often been attributed to corotating interaction regions (CIRs) like those seen in the solar wind. We present light curves for variable polarization from winds with CIR structures. We develop a model for a time-independent CIR based on a kinematical description. Assuming optically thin electron scattering, …
New Multiwavelength Observations Of The Of?P Star Cpd -28◦ 2561., S. Hubrig, M. Schöller, A. Kholtygin, H. Tsumura, A. Hoshino, S. Kitamoto, L. Oskinova, Richard Ignace, H. Todt, I. Ilyin
New Multiwavelength Observations Of The Of?P Star Cpd -28◦ 2561., S. Hubrig, M. Schöller, A. Kholtygin, H. Tsumura, A. Hoshino, S. Kitamoto, L. Oskinova, Richard Ignace, H. Todt, I. Ilyin
ETSU Faculty Works
A rather strong mean longitudinal magnetic field of the order of a few hundred gauss was detected a few years ago in the Of?p star CPD −28° 2561 using FORS2 (FOcal Reducer low dispersion Spectrograph 2) low-resolution spectropolarimetric observations. In this work, we present additional low-resolution spectropolarimetric observations obtained during several weeks in 2013 December using FORS 2 mounted at the 8-m Antu telescope of the Very Large Telescope (VLT). These observations cover a little less than half of the stellar rotation period of 73.41 d mentioned in the literature. The behaviour of the mean longitudinal magnetic field is consistent …
Searching For Chemical Signatures Of Multiple Stellar Populations In The Old, Massive Open Cluster Ngc 6791, Angela Bragaglia, Christopher Sneden, Eugenio Carretta, Raffaele G. Gratton, Sara Lucatello, Peter F. Bernath, James S. A. Brooke, Ram S. Ram
Searching For Chemical Signatures Of Multiple Stellar Populations In The Old, Massive Open Cluster Ngc 6791, Angela Bragaglia, Christopher Sneden, Eugenio Carretta, Raffaele G. Gratton, Sara Lucatello, Peter F. Bernath, James S. A. Brooke, Ram S. Ram
Chemistry & Biochemistry Faculty Publications
Galactic open and globular clusters (OCs, GCs) appear to inhabit separate regions of the age-mass plane. However, the transition between them is not easily defined because there is some overlap between high-mass, old OCs and low-mass, young GCs. We are exploring the possibility of a clear-cut separation between OCs and GCs using an abundance feature that has been found so far only in GCs: (anti)correlations between light elements. Among the coupled abundance trends, the Na-O anticorrelation is the most widely studied. These anticorrelations are the signature of self-enrichment, i.e., of a formation mechanism that implies multiple generations of stars. Here …
Small Carbon Chains In Circumstellar Envelopes, R. J. Hargreaves, K. Hinkle, P. F. Bernath
Small Carbon Chains In Circumstellar Envelopes, R. J. Hargreaves, K. Hinkle, P. F. Bernath
Chemistry & Biochemistry Faculty Publications
Observations of carbon-rich circumstellar envelopes were made using the Phoenix spectrograph on the Gemini South telescope to determine the abundance of small carbon chain molecules. Vibration-rotation lines of the ν3 antisymmetric stretch of C3 near 2040 cm-1 (4.902 μm) have been used to determine the column density for four carbon-rich circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We additionally calculate the column density of C5 for IRC +10216, and provide an upper limit for five more objects. An upper limit estimate for the C7 column density is also provided for IRC+10216. A …
Line Lists For The A2Π-X 2Σ+ (Red) And B2Σ+-X 2Σ+ (Violet) Systems Of Cn, 13c14n, And 12c15n, And Application To Astronomicalspectra, Christopher Sneden, Sara Lucatello, Ram S. Ram, James S. A. Brooke, Peter Bernath
Line Lists For The A2Π-X 2Σ+ (Red) And B2Σ+-X 2Σ+ (Violet) Systems Of Cn, 13c14n, And 12c15n, And Application To Astronomicalspectra, Christopher Sneden, Sara Lucatello, Ram S. Ram, James S. A. Brooke, Peter Bernath
Chemistry & Biochemistry Faculty Publications
New red and violet system line lists for the CN isotopologues 13C14N and 12C15N have been generated. These new transition data are combined with those previously derived for 12C14N, and applied to the determination of CNO abundances in the solar photosphere and in four red giant stars: Arcturus, the bright, very low-metallicity star HD 122563, and the carbon-enhanced metal-poor stars HD 196944 and HD 201626. When both red and violet system lines are detectable in a star, their derived N abundances are in good agreement. The mean N abundances determined in …
Characterizing The Ab Doradus Moving Group Via High-Resolution Spectroscopy And Kinematic Traceback, Kyle Mccarthy, Ronald J. Wilhelm
Characterizing The Ab Doradus Moving Group Via High-Resolution Spectroscopy And Kinematic Traceback, Kyle Mccarthy, Ronald J. Wilhelm
Physics and Astronomy Faculty Publications
We present a detailed analysis of 10 proposed F and G members of the nearby, young moving group AB Doradus (ABD). Our sample was obtained using the 2.7 m telescope at the McDonald Observatory with the coude echelle spectrograph, achieving R ~ 60,000 and signal-to-noise ratio ~200. We derive spectroscopic T eff, log(g), [Fe/H], and microturbulance (vt ) using a bootstrap method of the TGVIT software resulting in typical errors of 33K in T eff, 0.08 dex in log(g), 0.03 dex in [Fe/H], and 0.13 km s–1 in vt . …
Early-Type Galaxies In The Chandra Cosmos Survey, F. Civano, G. Fabbiano, S. Pellegrini, D.-W. Kim
Early-Type Galaxies In The Chandra Cosmos Survey, F. Civano, G. Fabbiano, S. Pellegrini, D.-W. Kim
Dartmouth Scholarship
We study a sample of 69 X-ray detected early-type galaxies (ETGs), selected from the Chandra COSMOS survey, to explore the relation between the X-ray luminosity of hot gaseous halos (L X, gas) and the integrated stellar luminosity (LK ) of the galaxies, in a range of redshift extending out to z = 1.5. In the local universe, a tight, steep relationship has been established between these two quantities, suggesting the presence of largely virialized halos in X-ray luminous systems. We use well-established relations from the study of local universe ETGs, together with the expected evolution …
The Calculation Of H-Beta Indices For Delta Scuti Variable Stars, Kelsey Jorgenson, Dr. Eric Hintz
The Calculation Of H-Beta Indices For Delta Scuti Variable Stars, Kelsey Jorgenson, Dr. Eric Hintz
Journal of Undergraduate Research
A large part of astronomical research involves gathering information about celestial objects and drawing conclusions about that information. Astronomers commonly gather data for research projects via sweeping surveys, either of particular regions of the sky or of specific kinds of stars or celestial objects. Data from these surveys are often arranged into catalogues. The aim of my research project was to fill in information gaps in the catalogue of information of known delta Scuti variable stars, particularly in the form of the hydrogen beta, or H-beta, index. I will give introductory information about delta Scuti stars as well as the …
Transit Timing Analysis In The Hat-P-32 System, M. Seeliger, D. P. Dimitrov, D. Kjurkchieva, M. Mallonn, M. Fernandez, M. Kitze, V. Casanova, G. Maciejewski, J. M. Ohlert, J. G. Schmidt, A. Pannicke, D. Puchalski, E. Gogus, T. Guver, S. Bilir, T. Ak, M. M. Hohle, T. O.B. Schmidt, R. Errmann, E.L.N. Jensen, D. H. Cohen, Laurence A. Marschall, G. Saral, I. Bernt, E. Derman, C. Galan, R. Neuhauser
Transit Timing Analysis In The Hat-P-32 System, M. Seeliger, D. P. Dimitrov, D. Kjurkchieva, M. Mallonn, M. Fernandez, M. Kitze, V. Casanova, G. Maciejewski, J. M. Ohlert, J. G. Schmidt, A. Pannicke, D. Puchalski, E. Gogus, T. Guver, S. Bilir, T. Ak, M. M. Hohle, T. O.B. Schmidt, R. Errmann, E.L.N. Jensen, D. H. Cohen, Laurence A. Marschall, G. Saral, I. Bernt, E. Derman, C. Galan, R. Neuhauser
Physics and Astronomy Faculty Publications
We present the results of 45 transit observations obtained for the transiting exoplanet HATP- 32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to …
1207-3900_Nir_Spex, Jonathan Gagné
1207-3900_Opt_Mage, Jonathan Gagné
Improved Line Data For The Swan System 12c13c Isotopologue, Ram S. Ram, James S. A. Brooke, Peter F. Bernath, Christopher Sneden, Sara Lucatello
Improved Line Data For The Swan System 12c13c Isotopologue, Ram S. Ram, James S. A. Brooke, Peter F. Bernath, Christopher Sneden, Sara Lucatello
Chemistry & Biochemistry Faculty Publications
We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the 12C 13C isotopologue Swan d3Π-a3Π system 0-0, 0-1, 0-2, 1-0, 1-1, 1-2, 2-0, 2-1, and 2-2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the 12C13C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The 12C13C line data were combined with similar data for 12C2, reported in a companion paper, and applied …