Search Publications
A Comprehensive Study of Five Intermediate-age Pismis (2, 3, 7, 12, 15) Clusters Using Photometric and Astrometric Data from Gaia EDR3
Bisht, D.; Rangwal, Geeta; Yadav, R. K. S. +5 more
Open clusters are groups of stars that form simultaneously; hence, these are excellent probes to test theories of star formation, stellar evolution, and dynamics in the Milky Way disk. We carry out a detailed photometric and kinematic study of five poorly studied intermediate-age open clusters, Pismis 2 (Pi 2), Pismis 3 (Pi 3), Pismis 7 (Pi 7), Pi…
Pulsating subdwarf B stars in the oldest open cluster NGC 6791
Reed, M. D.; Pelisoli, I.; Németh, P. +6 more
We report results of our analysis of the Kepler superaperture LC data of the open cluster NGC 6791 to search for pulsating sdB stars. We checked all pixels and we found only three sdB stars to be pulsating, KIC 2569576 (B3), KIC 2438324 (B4), and KIC 2437937 (B5). These stars were known to be pulsators before, though we extended data coverage dete…
The Fast Evolving, Tremendous Blue Superoutburst in ASASSN-21au Reveals a Dichotomy in the Outbursts of Long-period AM CVns
Heinke, C. O.; Cavecchi, Y.; Vanmunster, T. +4 more
ASASSN-21au is an ultracompact accreting white dwarf binary (AM CVn type) with a period of ~58 minutes. Using multiwavelength observations of the system, we discovered a dichotomy in the behavior of outbursts in AM CVns. The binary showed an initial increase in brightness that lasted for at least 82 days, followed by an additional increase that la…
The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants
Davenport, James R. A.; Dorn-Wallenstein, Trevor Z.; Levesque, Emily M. +3 more
Fast yellow pulsating supergiants (FYPS) are a recently discovered class of evolved massive pulsators. As candidate supergiant objects, and one of the few classes of pulsating evolved massive stars, these objects have incredible potential to change our understanding of the structure and evolution of massive stars. Here we examine the lightcurves o…
Optical and Near-infrared Excesses are Correlated in T Tauri Stars
Kraus, Adam L.; Sullivan, Kendall
Accretion is one of the defining characteristics of classical T Tauri stars, fueled by the presence of a circumstellar disk comprised of dust and gas. Accretion produces a UV and optical excess, while re-radiated emission at the inner edge of the dust component of the disk produces a near-infrared (NIR) excess. The interplay between stars and thei…
Detection of 125.5-day optical periodic modulation of the neutron star M51 ULX-8
Allak, S.
Studying Ultraluminous X-ray sources (ULXs) in the optical wavelengths provides important clues about the accretion mechanisms and the evolutionary processes of X-ray binary systems. In this study, three (C1, C2, and C3) possible optical counterparts were identified for well-known neutron star (NS) candidate M51 ULX-8 through advanced astrometry b…
New candidates for magnetar counterparts from a deep search with the Hubble Space Telescope
Lyman, J. D.; Kouveliotou, C.; Fruchter, A. S. +5 more
We report the discovery of six new magnetar counterpart candidates from deep near-infrared Hubble Space Telescope (HST) imaging. The new candidates are among a sample of 19 magnetars for which we present HST data obtained between 2018 and 2020. We confirm the variability of previously established near-infrared counterparts, and newly identify cand…
Characterizing the 3D Kinematics of Young Stars in the Radcliffe Wave
Alves, João; Speagle, Joshua S.; Zucker, Catherine +5 more
We present an analysis of the kinematics of the Radcliffe Wave, a 2.7 kpc long sinusoidal band of molecular clouds in the solar neighborhood recently detected via 3D dust mapping. With Gaia DR2 astrometry and spectroscopy, we analyze the 3D space velocities of ~1500 young stars along the Radcliffe Wave in action-angle space, using the motion of th…
A Comparative L-dwarf Sample Exploring the Interplay between Atmospheric Assumptions and Data Properties
Gonzales, Eileen C.; Marley, Mark; Faherty, Jacqueline K. +3 more
Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of five L dwarfs of similar effective temperature (T eff) or spectral type to compare their pressure-temperature (P-T) profiles. Additionally, we explore the impact of an …
Coevolution of Broad Emission Lines and X-Ray Spectrum in Changing-look AGNs
Liu, Hao; Wu, Qingwen; Lyu, Bing
Changing-look active galactic nuclei (CLAGNs) show the disappearance and reappearance of broad emission lines in a few years, which challenges the orientation-based AGN unification model. We reduce the X-ray data for five well-studied CLAGNs that show a strong change in broad emission lines in the past several decades. We find that the X-ray photo…