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We report the discovery of a bright (V=11.6 mag) eclipsing hot subdwarf binary of spectral type B with a late main sequence companion from the All Sky Automated Survey (ASAS 102322-3737.0). Such systems are called HW Vir stars after the…

Solar and Stellar Astrophysics · Physics 2015-06-15 V. Schaffenroth , S. Geier , H. Drechsel , U. Heber , P. Wils , R. H. Oestensen , P. F. L. Maxted , G. di Scala

We present the results of a photometric variability survey in the young open cluster Stock 14 and the surrounding fields. In total, we detected 103 variable stars of which 88 are new discoveries. We confirm short-period, low-amplitude light…

Solar and Stellar Astrophysics · Physics 2013-10-01 D. Drobek , A. Pigulski , R. R. Shobbrook , A. Narwid

We present photometric and spectroscopic analyses of gravity (g-mode) long-period pulsating hot subdwarf B (sdB) stars. We perform a detailed asteroseismic and spectroscopic analysis of five pulsating sdB stars observed with {\it TESS}…

Tidally tilted pulsators (TTPs) are an intriguing new class of oscillating stars in binary systems; in such stars, the pulsation axis coincides with the line of apsides, or semi-major axis, of the binary. All three TTPs discovered so far…

Solar and Stellar Astrophysics · Physics 2022-04-06 Rahul Jayaraman , Gerald Handler , Saul Rappaport , Jim Fuller , Donald W. Kurtz , Stéphane Charpinet , George Ricker

We present the results of a survey using the WASP archive to search for high frequency pulsations in F-, A- and B-type stars. Over 1.5 million targets have been searched for pulsations with amplitudes greater than 0.5 millimagnitude. We…

We present a variable star catalog of an extensive ground-based wide-field variability survey in the globular cluster omega Centauri. Using the ANU 40-inch (1m) telescope at Siding Spring Observatory, the cluster was observed with a 52'x52'…

Astrophysics · Physics 2008-11-26 David T. F Weldrake , Penny D Sackett , Terry J Bridges

KIC10001893 is one out of 19 subdwarf-B (sdB) pulsators observed by the Kepler spacecraft in its primary mission. In addition to tens of pulsation frequencies in the g-mode domain, its Fourier spectrum shows three weak peaks at very low…

Earth and Planetary Astrophysics · Physics 2014-11-05 R. Silvotti , S. Charpinet , E. Green , G. Fontaine , J. H. Telting , R. H. Ostensen , V. Van Grootel , A. S. Baran , S. Schuh , L. Fox Machado

We present new medium-band uvby Stromgren and broad-band VI photometry for the central regions of the globular cluster Omega Cen. From this photometry we have obtained differential reddening estimates relative to two other globular clusters…

We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short--period pulsating stars (P<0.25 days). Observations collected over three consecutive nights…

Hot subdwarf B stars are core-helium burning objects that have undergone envelope stripping, likely by a binary companion. Using high-speed photometry from the Transiting Exoplanet Survey Satellite, we have discovered the hot subdwarf BPM…

Solar and Stellar Astrophysics · Physics 2022-11-09 Bryce A. Smith , Brad N. Barlow , Benjamin Rosenthal , J. J. Hermes , Veronika Schaffenroth

We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic…

We report a new subdwarf B (sdB) pulsator, PG1142-037, discovered during the first full-length campaign of K2, the two-gyro mission of the Kepler space telescope. Fourteen periodicities have been detected between 0.9 and 2.5 hours with…

We have used the two-degree field (2dF) multi-fibre spectrograph of the Anglo-Australian Telescope to search for candidate members of the unusual globular cluster omega Centauri at and beyond the cluster tidal radius. Velocities with an…

Astrophysics · Physics 2009-11-13 G. S. Da Costa , M. G. Coleman

We present the goals, strategy and first results of the OmegaWhite survey: a wide-field high-cadence $g$-band synoptic survey which aims to unveil the Galactic population of short-period variable stars (with periods $<$ 80 min), including…

Solar and Stellar Astrophysics · Physics 2015-09-30 S. A. Macfarlane , R. Toma , G. Ramsay , P. J. Groot , P. A. Woudt , J. E. Drew , G. Barentsen , J. Eisloffel

As many as 10\% of OB-type stars have global magnetic fields, which is surprising given their internal structure is radiative near the surface. A direct probe of internal structure is pulsations, and some OB-type stars exhibit pressure…

Solar and Stellar Astrophysics · Physics 2021-04-14 Keivan G. Stassun , Guillermo Torres , Cole Johnston , Daniel J. Stevens , Dax L. Feliz , Marina Kounkel , Luke G. Bouma

We present the analysis of 3 hrs of a rapid time series of precise stellar radial velocity (RV) measurements (sigma = 4.5 m/s) of the cool Ap star Beta CrB. The integrated RV measurements spanning the wavelength interval 5000-6000 Ang. show…

Astrophysics · Physics 2009-11-10 Artie P. Hatzes , David E. Mkrtichian

Using light curves with $\sim$3 min cadence and a duration of 2 hrs made using the OmegaWhite survey, we present the results of a search for short-period variable stars in the field of 20 open clusters. We identified 92 variable stars in…

Solar and Stellar Astrophysics · Physics 2022-04-06 R. Toma , G. Ramsay , C. S. Jeffery , S. A. Macfarlane , P. Woudt , P. J. Groot

We made photometric and spectroscopic observations of the rapidly pulsating subdwarf B star EC 09582-1137 with the aim of determining the target's fundamental structural parameters from asteroseismology. The new data comprise ~ 30 hours of…

Solar and Stellar Astrophysics · Physics 2015-05-14 S. K. Randall , V. Van Grootel , G. Fontaine , S. Charpinet , P. Brassard

Within the context of the "B fields in OB stars (BOB)" collaboration, we used the HARPSpol spectropolarimeter to observe the early B-type stars beta CMa (HD44743; B1 II/III) and epsilon CMa (HD52089; B1.5 II). For both stars, we…

We review the nature of the oscillations of main-sequence and supergiant stars of spectral type B. Seismic tuning of the interior structure parameters of the $\beta $Cep stars has been achieved since three years. The results are based on…

Astrophysics · Physics 2007-05-23 C. Aerts