Search Publications
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…
Our Galaxy's youngest disc
Li, Chengdong; Binney, James
We investigate the structure of our Galaxy's young stellar disc by fitting the distribution functions (DFs) of a new family to 5D Gaia data for a sample of $47\, 000$ OB stars. Tests of the fitting procedure show that the young disc's DF would be strongly constrained by Gaia data if the distribution of Galactic dust were accurately known. The DF t…
Magnetic field topology, chemical spot distributions, and photometric variability of the Ap star φ Draconis
Neiner, C.; Kochukhov, O.; Papakonstantinou, N.
The primary component of the multiple star φ Dra is one of the brightest magnetic chemically peculiar stars in the northern sky. Here, we report results of a comprehensive study of the rotational photometric variability, binarity, magnetic field geometry, and surface chemical spot structure for this star. We derived a precise photometric rotationa…
The pre-He white dwarfs in eclipsing binaries - IV. WASP 1814+48 with multiperiodic pulsations
Hong, Kyeongsoo; Lee, Jae Woo; Park, Jang-Ho +1 more
For the EL CVn candidate 1SWASPJ181417.43+481117.0 (WASP 1814+48), we secured the first spectroscopic observations between 2015 April and 2021 March. Using the echelle spectra, the radial velocities (RVs) of the primary star were measured with its atmospheric parameters of Teff, 1 = 7770 ± 130 K and $v$1sin i = 47 ± 6 km s