Open Access. Powered by Scholars. Published by Universities.®

Stars, Interstellar Medium and the Galaxy Commons

Open Access. Powered by Scholars. Published by Universities.®

878 Full-Text Articles 2,150 Authors 32,076 Downloads 62 Institutions

All Articles in Stars, Interstellar Medium and the Galaxy

Faceted Search

878 full-text articles. Page 5 of 25.

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey L. Carlin, David J. Sand, Ricardo R. Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan A. Forbes, Jonathan Hargis, Evan Kirby, Annika H.G. Peter, Aaron J. Romanowsky, Jay Strader 2017 LSST and Steward Observatory

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey L. Carlin, David J. Sand, Ricardo R. Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan A. Forbes, Jonathan Hargis, Evan Kirby, Annika H.G. Peter, Aaron J. Romanowsky, Jay Strader

Aaron J. Romanowsky

We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color–magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find  for Col I and  for Tri II, with corresponding half-light radii of  pc and  pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and ...


An X-Ray Study Of Two B+B Binaries: Ah Cep And Cw Cep, Richard Ignace, K. T. Hole, Lidia M. Oskinova, J. P. Rotter 2017 East Tennessee State University

An X-Ray Study Of Two B+B Binaries: Ah Cep And Cw Cep, Richard Ignace, K. T. Hole, Lidia M. Oskinova, J. P. Rotter

ETSU Faculty Works

AH Cep and CW Cep are both early B-type binaries with short orbital periods of 1.8 days and 2.7 days, respectively. All four components are B0.5V types. The binaries are also double-lined spectroscopic and eclipsing. Consequently, solutions for orbital and stellar parameters make the pair of binaries ideal targets for a study of the colliding winds between two B stars. Chandra ACIS-I observations were obtained to determine X-ray luminosities. AH Cep was detected with an unabsorbed X-ray luminosity at a 90% confidence interval of erg s−1, or , relative to the combined Bolometric luminosities of the two ...


Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron Romanowsky, Pieter van Dokkum 2017 University of California, Santa Cruz

Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron Romanowsky, Pieter Van Dokkum

Faculty Publications

Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption-line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (IMF) varies within the massive early-type galaxy (ETG) population. However, the physical mechanism that drives variation in the IMF is an outstanding question. Here we use new SPS models to consider a diverse set of compact, low-velocity dispersion stellar systems: globular clusters (GCs), an ultra-compact dwarf (UCD), and the compact elliptical (cE) galaxy M32. We compare our results to massive ETGs and available dynamical measurements. We find that the GCs have stellar mass-to-light ratios (M/L) that are ...


Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron J. Romanowsky, Pieter van Dokkum 2017 University of California, Santa Cruz

Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron J. Romanowsky, Pieter Van Dokkum

Aaron J. Romanowsky

Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption-line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (IMF) varies within the massive early-type galaxy (ETG) population. However, the physical mechanism that drives variation in the IMF is an outstanding question. Here we use new SPS models to consider a diverse set of compact, low-velocity dispersion stellar systems: globular clusters (GCs), an ultra-compact dwarf (UCD), and the compact elliptical (cE) galaxy M32. We compare our results to massive ETGs and available dynamical measurements. We find that the GCs have stellar mass-to-light ratios (M/L) that are ...


Book Review: Chandra's Cosmos: Dark Matter, Black Holes, And Other Wonders Revealed By Nasa's Premier X-Ray Observatory, T. D. Oswalt 2017 Embry-Riddle Aeronautical University

Book Review: Chandra's Cosmos: Dark Matter, Black Holes, And Other Wonders Revealed By Nasa's Premier X-Ray Observatory, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Chandra's cosmos: dark matter, black holes, and other wonders revealed by NASA's premier X-ray observatory by Wallace H. Tucker. Smithsonian Books, 2017. 266p bibl index ISBN 9781588345875, $29.95; ISBN 9781588345882 ebook, contact publiser for price.


The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister Graham, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader 2017 Swinburne University of Technology

The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister Graham, Duncan Forbes, Aaron Romanowsky, Jean Brodie, Jay Strader

Faculty Publications

We present radial tracks for four early-type galaxies with embedded intermediate-scale discs in a modified spin-ellipticity diagram. Here, each galaxy's spin and ellipticity profiles are shown as a radial track, as opposed to a single, flux-weighted aperture-dependent value as is common in the literature. The use of a single ellipticity and spin parameter is inadequate to capture the basic nature of these galaxies, which transition from fast to slow rotation as one moves to larger radii where the disc ceases to dominate. After peaking, the four galaxy's radial tracks feature a downturn in both ellipticity and spin with ...


The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister W. Graham, Duncan A. Forbes, Aaron J. Romanowsky, Jean P. Brodie, Jay Strader 2017 Swinburne University of Technology

The Sluggs Survey: Trails Of Sluggs Galaxies In A Modified Spin-Ellipticity Diagram, Sabine Bellstedt, Alister W. Graham, Duncan A. Forbes, Aaron J. Romanowsky, Jean P. Brodie, Jay Strader

Aaron J. Romanowsky

We present radial tracks for four early-type galaxies with embedded intermediate-scale discs in a modified spin-ellipticity diagram. Here, each galaxy's spin and ellipticity profiles are shown as a radial track, as opposed to a single, flux-weighted aperture-dependent value as is common in the literature. The use of a single ellipticity and spin parameter is inadequate to capture the basic nature of these galaxies, which transition from fast to slow rotation as one moves to larger radii where the disc ceases to dominate. After peaking, the four galaxy's radial tracks feature a downturn in both ellipticity and spin with ...


"Blinded By The Lines: Mid-Ir Spectra Of Mira Variables Taken With Spitzer", Dana Baylis-Aguirre, Michelle J. Creech-Eakman, Donald G. Luttermoser, Tina Gueth 2017 New Mexico Institute of Mining and Technology

"Blinded By The Lines: Mid-Ir Spectra Of Mira Variables Taken With Spitzer", Dana Baylis-Aguirre, Michelle J. Creech-Eakman, Donald G. Luttermoser, Tina Gueth

Donald G. Luttermoser

We present preliminary analysis of mid-infrared spectra of M-type and C-type Mira variables. Due to the brightness of this sample, it is straightforward to monitor changes with phase in the infrared spectral features of these regular pulsators. We have spectra of 25 Mira variables, taken with phase, using the Spitzer Infrared Spectrograph (IRS) high-resolution module. Each star has multiple spectra obtained over a one-year period from 2008-09. This is a rich, unique data set due to multiple observations of each star and the high signal-to-noise ratio from quick exposure times to prevent saturation of the IRS instrument. This paper focuses ...


Bringing Awe Down To Earth: Inspiring High Performance Through Positive Executive Coaching, Chad Thomas 2017 University of Pennsylvania

Bringing Awe Down To Earth: Inspiring High Performance Through Positive Executive Coaching, Chad Thomas

Master of Applied Positive Psychology (MAPP) Capstone Projects

What inspires and sustains high performance? Positive psychology, the scientific study of human strengths and well-being, provides evidence-based insights into the mechanisms of, and characteristics associated with, flourishing. Astronauts represent a paragon of high performance through the intensely focused preparation, passion, and perseverance required in their training and during space missions. This capstone draws on both scientific findings from positive psychology and insights from astronaut training to provide a unique lens for a positive executive coaching program. In addition to a review of relevant positive psychology research to illustrate the principles of this program, this capstone includes personal anecdotes and ...


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 2017 University of Toronto

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 from ...


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 2017 University of Postdam

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 2017 Chinese Academy of Sciences

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 ...


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 2017 Chinese Academy of Sciences

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 UV velocity and metallicity distributions of the local sample show a clear gap between the Hercules structure and the Hyades–Pleiades structure. The U ...


Magnetospherically-Trapped Dust And A Possible Model For The Unusual Transits At Wd1145+017, J. Farihi, Ted von Hippel, J. E. Pringle 2017 University College London

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 ...


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 2017 Swinburne University of Technology

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.


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

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

Aaron J. Romanowsky

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


Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey 2017 The Graduate Center, City University of New York

Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey

All Dissertations, Theses, and Capstone Projects

Exoplanet direct detections are reaching the temperature regime of cool brown dwarfs, motivating further understanding of the coolest substellar atmospheres. These objects, T and Y dwarfs, are numerous and isolated in the field, thus making them easier to study in detail than objects in companion systems. Brown dwarf spectral types are derived from spectral morphology and generally appear to correspond with decreasing mass and effective temperature (Teff). However, spectral subclasses of the colder objects do not share this monotonic temperature correlation, indicating that secondary parameters (gravity, metallicity, dust) significantly influence spectral morphology. These secondary atmospheric parameters can provide insight ...


Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory 2017 kgrego12

Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory

Chancellor’s Honors Program Projects

No abstract provided.


Revealing The Structure Of The Outer Disks Of Be Stars, Robert Klement, Anthony C. Carciofi, Thomas Rivinius, Lynn D. Matthews, Rodrigo G. Vieira, Richard Ignace, Jon E. Bjorkman, B. C. Mota, Daniel M. Faes, A. D. Bratcher, M. Cure, Stanislav Stefl 2017 European Southern Observatory

Revealing The Structure Of The Outer Disks Of Be Stars, Robert Klement, Anthony C. Carciofi, Thomas Rivinius, Lynn D. Matthews, Rodrigo G. Vieira, Richard Ignace, Jon E. Bjorkman, B. C. Mota, Daniel M. Faes, A. D. Bratcher, M. Cure, Stanislav Stefl

ETSU Faculty Works

Context. The structure of the inner parts of Be star disks (≲ 20 stellar radii) is well explained by the viscous decretion disk (VDD) model, which is able to reproduce the observable properties of most of the objects studied so far. The outer parts, on the other hand, are not observationally well-explored, as they are observable only at radio wavelengths. A steepening of the spectral slope somewhere between infrared and radio wavelengths was reported for several Be stars that were previously detected in the radio, but a convincing physical explanation for this trend has not yet been provided.

Aims. We test ...


Have We Found Our Neighbors? The Search For Habitable Planets Outside Our Solar System, Madeline Galbraith 2017 Duquesne University

Have We Found Our Neighbors? The Search For Habitable Planets Outside Our Solar System, Madeline Galbraith

D.U.Quark

No abstract provided.


Digital Commons powered by bepress