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Atomic diffusion in the atmosphere of Feige 86
Németh, Péter
We have revisited the ultraviolet and optical spectra of the blue horizontal branch star Feige 86. The new analysis finds the star cooler and more compact than previously determined. The IUE spectrum of Feige 86 holds numerous unidentified spectral lines of heavy metals, indicating efficient atomic diffusion in the atmosphere. Because diffusion pl…
OB Stars and Cepheids From the Gaia TGAS Catalogue: Test of their Distances and Proper Motions
Bobylev, Vadim V.; Bajkova, Anisa T.
We consider young distant stars from the Gaia TGAS catalog. These are 250 classical Cepheids and 244 OB stars located at distances up to 4 kpc from the Sun. These stars are used to determine the Galactic rotation parameters using both trigonometric parallaxes and proper motions of the TGAS stars. In this case the considered stars have relative par…
A preliminary comparison of photometric (MWSC) and trigonometric (TGAS) distances of open cluster stars
Scholz, Ralf-Dieter; Kovaleva, Dana; Piskunov, Anatoly +1 more
The goal of this researchwas to compare the open cluster photometric distance scale of the global survey of star clusters in the MilkyWay (MWSC) with the distances derived fromtrigonometric parallaxes fromthe Gaia DR1/TGAS catalogue and to investigate towhich degree and extent both scales agree.We compared the parallax-based and photometrybased di…
News on the X-ray emission from hot subdwarf stars
Mereghetti, Sandro; Palombara, Nicola La
In latest years, the high sensitivity of the instruments on-board the XMM-Newton and Chandra satellites allowed us to explore the properties of the X-ray emission from hot subdwarf stars. The small but growing sample of X-ray detected hot subdwarfs includes binary systems, in which the X-ray emission is due to wind accretion onto a compact compani…