Search Publications
The Energetics of the Central Engine in the Powerful Quasar 3C 298
Schneider, Donald P.; Zeimann, Gregory R.; Hill, Gary J. +3 more
The compact steep-spectrum radio source 3C 298 (redshift of 1.44) has the largest 178 MHz luminosity in the Third Cambridge Revised Catalogue (3CR); its radio lobes are among the most luminous in the universe. The plasma state of the radio lobes is modeled with the aid of interferometric radio observations (in particular, the new Low Frequency Arr…
HD 183986: A High-contrast SB2 System with a Pulsating Component
Gajdoš, Pavol; Vaňko, Martin; Pribulla, Theodor +7 more
There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this hypothesis by a more detailed spectroscopic and photometric investigation of one such object: HD 183986. We obta…
HST STIS Observations of ζ Aurigae A's Irradiated Atmosphere
Ayres, Thomas R.; Harper, Graham M.; Bennett, Philip D. +3 more
The details of the processes responsible for heating the chromospheres of evolved cool stars remain uncertain. While most spectroscopic diagnostics measure spatially-integrated emission, here we examine diagnostics sensitive to localized atmospheric regions that are specific to cool evolved stars in binary systems with hot main-sequence companions…
X-Ray Emission from Candidate Stellar Merger Remnant TYC 2597-735-1 and Its Blue Ring Nebula
Hoadley, Keri; Schneider, P. C.; Günther, Maximilian N. +3 more
Tight binary or multiple-star systems can interact through mass transfer and follow vastly different evolutionary pathways than single stars. The star TYC 2597-735-1 is a candidate for a recent stellar merger remnant resulting from a coalescence of a low-mass companion with a primary star a few thousand years ago. This violent event is evident in …
Coaxing the Eclipsing Binary V367 Cygni out of Its Shell
Davidge, T. J.
Spectra that cover 0.63-0.69 µm with a spectral resolution ~17,000 are presented of the W Serpentis system V367 Cygni. Absorption lines of Fe II and Si II that form in a circumsystem shell are prominent features, and the depths of these are stable with time, suggesting that the shell is smoothly distributed and well mixed. Further evidence o…
Chemical Abundances of Eight Highly-extincted Milky Way Planetary Nebulae
Dinerstein, Harriet L.; Zeimann, Greg; Sterling, N. C. +1 more
Low- and intermediate-mass (0.8 M ⊙ < M < 8 M ⊙) stars that evolve into planetary nebulae (PNe) play an important role in tracing and driving Galactic chemical evolution. Spectroscopy of PNe enables access to both the initial composition of their progenitor stars and products of their internal nucleosynthesis, but deter…
Challenging the Disk Instability Model. I. The Case of YZ LMi
Baptista, Raymundo; Schlindwein, Wagner
Observations of YZ LMi show enhanced emission along the stream trajectory beyond impact at the disk rim during outbursts as well as when the quiescent disk is large. We investigated whether these features can be explained in terms of either gas stream overflow or penetration within the frameworks of the disk instability model (DIM) and the mass-tr…
An Analysis of the Eclipsing Binaries HD 71636, V1022 Cassiopeiae, and OT Andromedae
Henry, Gregory W.; Fekel, Francis C.; Sowell, James R. +3 more
We have obtained high-dispersion spectroscopy and BV photometry of two F-type eclipsing binaries, HD 71636 and V1022 Cas, plus the A-type system OT And. Transiting Exoplanet Survey Satellite measurements for each system have also been incorporated. The photometry of HD 71636 enables a more consistent picture of this 5.01331 days, circular-orbit sy…
Locating Red Supergiants in the Galaxy NGC 6822
Massey, Philip; Levesque, Emily M.; Neugent, Kathryn F. +1 more
Using archival near-IR photometry, we identify 51 of the K-band brightest red supergiants (RSGs) in NGC 6822 and compare their physical properties with stellar evolutionary model predictions. We first use Gaia parallax and proper motion values to filter out foreground Galactic red dwarfs before constructing a J-K versus K color-magnitude diagram t…
OGLE-2014-BLG-0319: A Sub-Jupiter-mass Planetary Event Encountered Degeneracy with Different Mass Ratios and Lens-source Relative Proper Motions
Udalski, Andrzej; Mróz, Przemek; Skowron, Jan +37 more
We report the discovery of a sub-Jovian-mass planet, OGLE-2014-BLG-0319Lb. The characteristics of this planet will be added into a future extended statistical analysis of the Microlensing Observations in Astrophysics (MOA) collaboration. The planetary anomaly of the light curve is characterized by MOA and OGLE survey observations and results in th…