Publications (13)
First Stars. II. Evolution with mass loss
David Bahena, Petr Hadrava
The first stars are assumed to be predominantly massive. Although, due to the low initial abundances of heavy elements the line-driven stellar winds are supposed to be inefficient…
VO-KOREL: A Fourier disentangling service of Virtual Observatory
Petr Å koda, Petr Hadrava, Jan Fuchs
VO-KOREL is a web service exploiting the technology of Virtual Observatory for providing the astronomers with the intuitive graphical front-end and distributed computing back-end r…
Optical Spectroscopic Observations of Cyg X-1=HDE 226868
Jingzhi Yan, Qingzhong Liu, Petr Hadrava
We present the results of the spectroscopic observations of HDE 226868, the optical counterpart to the black hole X-ray binary Cyg X-1, from 2001 to 2006. We analyze the variabilit…
Optical spectroscopy of Cyg X-1
Petr Hadrava
The star HDE 226868 known as an optical counterpart of the black hole candidate Cyg X-1 has been observed in H_alpha region using spectrograph at Ondrejov 2-m telescope. The orbita…
Interpreting the X-ray state transitions of Cygnus X-1
Jan Äechura, Saeqa Dil Vrtilek, Petr Hadrava
We present a novel method for interpreting observations of high-mass X-ray binaries (HMXBs) based on a combination of spectroscopic data and numerical results from a radiation hydr…
Gem: a hierarchical triple system with an outer Be star
Robert Klement, Petr Hadrava, Thomas Rivinius +17
Time series of spectroscopic, speckle-interferometric, and optical long-baseline-interferometric observations confirm that Gem is a hierarchical triple system. It consists of…