Search Publications
A Magnetic Valve at L1 Revealed in TESS Photometry of the Asynchronous Polar BY Cam
Ramsay, Gavin; Garnavich, Peter; Littlefield, Colin +7 more
We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat cycle between the 199.384 min white dwarf (WD) spin period and the 201.244 min orbital period. This results in changes in the flow of matter onto the WD. The TESS light curve covers 92% of the beat cycle once and 71% of the beat cycle twice. The strongest photometr…
Swift J0503.7-2819: a Short-period Asynchronous Polar or Stream-fed Intermediate Polar
Halpern, J. P.
We analyze a 7.4 hr XMM-Newton light curve of the cataclysmic variable Swift J0503.7-2819, previously classified using optical periods as an intermediate polar (IP) with an orbital period of 0.0567 days. A photometric signal at 975 s, previously suggested to be the spin period, is not present in X-rays and is readily understood as a quasiperiodic …
He-star donor AM CVn stars and their progenitors as LISA sources
Yungelson, L.; Liu, W. -M.; Kuranov, A.
Context. Ultracompact cataclysmic variables (CVs) of the AM CVn type are deemed to be important verification sources for the future space gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA).
Aims: We model the present-day Galactic population of AM CVn stars with He-star donors. Such a population has long expecte…
Robust Inference of Neutron-star Parameters from Thermonuclear Burst Observations
Galloway, Duncan K.; Goodwin, Adelle; Johnston, Zac +1 more
Thermonuclear (type-I) bursts arise from unstable ignition of accumulated fuel on the surface of neutron stars in low-mass X-ray binaries. Measurements of burst properties in principle enable observers to infer the properties of the host neutron star and mass donors, but a number of confounding astrophysical effects contribute to systematic uncert…
A first eROSITA view of ultracool dwarfs
Salvato, M.; Stelzer, B.; Coffaro, M. +2 more
We present the first X-ray detections of ultracool dwarfs (UCDs) from the first all-sky survey of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) onboard the Russian Spektrum-Roentgen-Gamma mission. We use three publicly available input catalogs of spectroscopically confirmed UCDs and Gaia-selected UCD candidates that togeth…
The Internal Line-of-Sight Kinematics of NGC 346: The Rotation of the Core Region
Sabbi, Elena; Nota, Antonella; Zeidler, Peter
We present the stellar radial velocity analysis of the central $1^{\prime} \times 1^{\prime} $ of the young massive Small Magellanic Cloud star cluster NGC 346. Using VLT/MUSE integral field spectroscopy in combination with Hubble Space Telescope photometry, we extract 103 spectra of cluster member stars suited to measure accurate line-of-sight ki…
An X-ray view of the ambiguous nuclear transient AT2019pev
Kochanek, C. S.; Grupe, D.; Mathur, S. +3 more
AT2019pev is a nuclear transient in a narrow-line Seyfert 1 galaxy at z = 0.096. The archival ultraviolet, optical, and infrared data showed features of both tidal disruption events and active galactic nuclei (AGNs), and its nature is not fully understood. We present detailed X-ray observations of AT2019pev taken with Swift, Chandra, and NICER ove…
Emission line star catalogues post-Gaia DR3. A validation of Gaia DR3 data using the LAMOST OBA emission catalogue
Arun, R.; Manoj, P.; Paul, K. T. +9 more
Aims.Gaia Data Release 3 (DR3) and further releases have the potential to identify and categorise new emission-line stars in the Galaxy. We perform a comprehensive validation of astrophysical parameters from Gaia DR3 with the spectroscopically estimated emission-line star parameters from the LAMOST OBA emission catalogue. Method. We compare differ…
Effect of Differential Rotation on the Magnetic Braking of Low-mass and Solar-like Stars: A Proof-of-concept Study
Finley, Adam J.; Matt, Sean P.; Ireland, Lewis G. +4 more
On the main sequence, low-mass and solar-like stars are observed to spin down over time, and magnetized stellar winds are thought to be predominantly responsible for this significant angular momentum loss. Previous studies have demonstrated that the wind torque can be predicted via formulations dependent on stellar properties, such as magnetic fie…
Double-lined spectroscopic binaries in M11
Kovalev, Mikhail; Straumit, Ilya
We have developed a new method for spectral analysis of binaries. Our method successfully identifies double-lined spectroscopic binary (SB2) candidates from high-resolution Gaia-ESO spectra. Compared to the commonly used cross-correlation function analysis, it works for binaries with rapidly rotating components. We test our method on synthetic and…