Search Publications
Search for OB associations in Gaia Early Data Release 3
de Grijs, Richard; Chemel, Alexander A.; Glushkova, Elena V. +1 more
The distribution of young stars into OB associations has long been in need of updating. High-precision Gaia Early Data Release 3 astrometry, coupled with modern machine-learning methods, allows this to be done. We have compiled a well-defined sample which includes OB stars and young open clusters (OCs), in total comprising about 47 700 objects. To…
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…
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…
Impact of ionization and electron density gradients in X-ray reflection spectroscopy measurements
Tripathi, Ashutosh; Abdikamalov, Askar B.; Bambi, Cosimo +1 more
The models currently used for the analysis of the reflection spectra of black holes usually assume a disc with constant ionization and electron density. However, there is some debate on the impact of these assumptions on the estimate of the properties of the sources, in particular when the fits suggest very steep emissivity profiles in the inner p…
Tracking X-ray outflows with optical/infrared footprint lines
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +5 more
We use cloudy photoionization models to predict the flux profiles for optical/infrared (IR) emission lines that trace the footprint of X-ray gas, such as [Fe X] 6375 Å and [Si X] 1.43 $\mu\mathrm{m}$. These are subset of coronal lines, from ions with ionization potential greater than or equal to that of O VII, i.e. 138 eV. The footprint lines are …
System parameters of three short-period cataclysmic variable stars
Dhillon, V. S.; Breedt, E.; Marsh, T. R. +9 more
Using photometric ULTRACAM observations of three new short-period cataclysmic variables (CVs), we model the primary eclipse light curves to extract the orbital separation, masses, and radii of their component stars. We find donor masses of $0.060\pm 0.008\, {\rm M_\odot }$, $0.042\pm 0.001\, {\rm M_\odot }$, and $0.042\pm 0.004\, {\rm M_\odot }$, …
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS - IV. Discovery of two new GW Vir stars: TIC 0403800675 and TIC 1989122424
Kepler, S. O.; Córsico, Alejandro H.; Uzundag, Murat +4 more
We present two new GW Vir-type pulsating white dwarf stars, TIC 0403800675 (WD J115727.68-280349.64) and TIC 1989122424 (WD J211738.38-552801.18) discovered in the Transiting Exoplanet Survey Satellite (TESS) photometric data. For both stars, the TESS light curves reveal the presence of oscillations with periods in a narrow range between 400 and 4…
A large catalogue of molecular clouds in the Southern sky
Chen, B. -Q.; Liu, X. -W.; Guo, H. -L.
We present a large catalogue of molecular clouds with accurate distance estimates in the Southern sky. Based on the three-dimensional dust extinction map and the best-fitting extinction and distance information of over 17 million stars presented in Guo et al. (2021, ApJ, 906, 47), we have identified 250 dust/molecular clouds in the Southern sky us…
Low-mass members of nearby young stellar moving groups from Gaia EDR3
Murphy, Simon J.; Song, Inseok; Lee, Jinhee
Gaia EDR3 offers greatly improved kinematics for nearby objects, including members of nearby young stellar moving groups (NYMGs). In this study, we aim to identify low-mass NYMG members (spectral types of M0 to mid-L) in Gaia EDR3. We calculated spatio-kinematic membership probabilities by utilizing a Bayesian membership probability calculation sc…