Related papers: Why do hot subdwarf stars pulsate?
The hosts of long duration gamma-ray bursts are predominantly starburst galaxies at subsolar metallicity. At redshifts z<1, this implies that most of them are low-mass galaxies similar to the populations of blue compact dwarfs and dwarf…
We present five new pulsating subdwarf B (sdB) stars discovered by the Kepler spacecraft during the asteroseismology survey phase. We perform time-series analysis on the nearly continuous month-long Kepler datasets of these 5 objects; these…
The recent variability survey of the NGC 3766 cluster revealed a considerable number of periodic variable stars in a region of the H-R diagram where no pulsation is expected. This region lies between the instability strips of the delta…
Several studies have shown that a number of stars pulsating in p modes lie between the $\beta$ Cep and $\delta$ Sct instability strips in the Hertzsprung-Russell (HR) Diagram. At present, there is no certain understanding of how p~modes can…
Context. The nature of the recently identified "sdA" spectroscopic class of star is not well understood. The thousands of known sdAs have H-dominated spectra, spectroscopic surface gravities intermediate to main sequence stars and isolated…
One of the most dramatic events in the life of a low-mass star is the He flash, which takes place at the tip of the red giant branch (RGB) and is followed by a series of secondary flashes before the star settles into the zero-age horizontal…
We report the detection of velocity variations in the pulsating sdB star, PG 1605+072. Oscillations are detected at the same frequencies found from photometry and have amplitudes of up to 14 km/s for H$\beta$. The strongest oscillation…
The long-time photometric surveys in a few young open clusters allowed to identify the light variability in stars located on the HR diagram between the well defined $\delta$ Scuti variables and Slowly Pulsating B-type stars. Several objects…
Classification of over 50000 TESS stars in sectors 1-18 has resulted in the detection of 766 pulsating main sequence B stars as well as over 5000 $\delta$ Scuti, 2300 $\gamma$ Doradus and 114 roAp candidates. It is found that a distinct…
The existence of faint blue stars far above the galactic plane, which have spectra that are similar to nearby Population I B stars, present several interesting questions. Among them are: Can a Population I B star travel from the disk to a…
We have carried out a detailed binary populations synthesis (BPS) study of the formation of subdwarf B (sdB) stars and related objects (sdO, sdOB stars) using the latest version of the BPS code developed by Han et al.(1994, 1995a, 1995b,…
Hot subdwarf B (sdB) stars are helium core burning stars that have lost almost their entire hydrogen envelope due to binary interaction. Their assumed canonical mass of $\rm M_{\mathrm{sdB}}\sim0.47 M_{\odot}$ has recently been debated…
The tidally tilted pulsators are a new type of oscillating star in close binary systems that have their pulsation axis in the orbital plane because of the tidal distortion caused by their companion. We describe this group of stars on the…
There are many Slowly Pulsating B (SPB) stars and gamma Dor stars in the Kepler Mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric…
Numerical computations of stellar oscillations for models representative of B-type stars predict fewer modes to be excited than observations reveal from modern space-based photometric data. One shortcoming of state-of-the-art evolution…
We present the first results of a survey of blue horizontal branch (BHB) stars in the Galactic bulge. 164 candidates with 15 < V < 17.5 in a field 7.5deg from the Galactic Center were observed in the blue at 2.4A FWHM resolution with the…
Context: [abbreviated] Aims: Kepler data of three known Be stars are re-visited to establish their pulsational nature and assess the properties of additional, non-pulsational variations. The three program stars turned out to be one inactive…
Starburst (SB) galaxies are a rare population of galaxies with star formation rates (SFRs) greatly exceeding those of the majority of star-forming galaxies with similar stellar mass. It is unclear whether these bursts are the result of…
Recent observations and theories suggest that extreme horizontal branch (EHB) stars and their progeny should be the cause of the UV excess seen in the spectra of many elliptical galaxies. Since the Galactic Bulge is the closest…
Four members of the new class of pulsating sdB stars are analysed from Keck HIRES spectra using NLTE and LTE model atmospheres. Atmospheric parameters (Teff, log g, log(He/H)), metal abundances and rotational velocities are determined.…