Publications (18)
The Ultraviolet Spectrum and Physical Properties of the Mass Donor Star in HD 226868 = Cygnus X-1
S. M. Caballero-Nieves, D. R. Gies, C. T. Bolton +8
We present an examination of high resolution, ultraviolet spectroscopy from Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the massive X-ray binary HD 2…
On the long cycle variability of the Algol OGLE-LMC-DPV-065 and its stellar, orbital and disk parameters
R. E. Mennickent, M. Cabezas, G. DjuraÅ¡eviÄ +13
OGLE-LMC-DPV-065 is an interacting binary whose double-hump long photometric cycle remains hitherto unexplained. We analyze photometric time series available in archive datasets sp…
Spectroscopy of the massive interacting binary UU Cassiopeiae
P. Hadrava, M. Cabezas, G. DjuraÅ¡eviÄ +9
Context. The eclipsing close binary UU Cas is an interacting massive double-periodic system with a gainer star partly hidden in an accretion disk. Aims. In order to study the physi…
Newborn Be star systems observed shortly after mass transfer
Th. Rivinius, R. Klement, S. D. Chojnowski +24
Many classical Be stars acquire their very rapid rotation by mass and angular-momentum transfer in massive binaries. Short-lived intermediate-phase objects have only been discovere…
VLTI/GRAVITY enables the determination of the first dynamical masses of a classical Be + stripped and bloated pre-subdwarf binary
R. Klement, Th. Rivinius, D. Baade +7
HR~6819 is the first post-mass transfer binary system composed of a classical Be star and a bloated pre-subdwarf stripped star directly confirmed by interferometry. While the Be st…
HR 6819 is a binary system with no black hole -- revisiting the source with infrared interferometry and optical integral field spectroscopy
A. J. Frost, J. Bodensteiner, Th. Rivinius +16
Two scenarios have been proposed to match the existing observational constraints of the object HR 6819. The system could consist of a close inner B-type giant plus a black hole (BH…
A naked-eye triple system with a nonaccreting black hole in the inner binary
Th. Rivinius, D. Baade, P. Hadrava +2
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d bi…
Properties and nature of Be stars. XX. Binary nature and orbital elements of gamma Cas
P. Harmanec, P. Habuda, S. Stefl +8
An analysis of accurate radial velocities (RVs) of the Be star gamma Cas from 295 Reticon spectrograms secured between October 1993 and May 2000 allowed us to prewhiten the RVs for…
Disentangling the stellar atmosphere and the focused wind in different accretion states of Cygnus X-1
M. Brigitte, P. Hadrava, B. Kubátová +8
In high-mass X-ray binaries (HMXBs), the compact object accretes the strong stellar wind of an O-B supergiant companion star. X-ray flux variations alter the stellar wind's ionizat…
HD172189: another step in furnishing one of the best laboratories known for asteroseismic studies
O. L. Creevey, K. Uytterhoeven, S. MartÃn-Ruiz +25
HD172189 is a spectroscopic eclipsing binary system with a rapidly-rotating pulsating delta Scuti component. It is also a member of the open cluster IC4756. These combined characte…
Notes on disentangling of spectra II. Intrinsic line-profile variability due to Cepheid pulsations
P. Hadrava, M. Slechta, P. Skoda
The determination of pulsation velocities from observed spectra of Cepheids is needed for the Baade-Wesselink calibration of these primary distance markers. The applicability of th…
Properties and nature of Be stars XXIII. Long-term variations and physical properties of kappa Dra
S. M. Saad, J. Kubat, P. Koubsky +9
We present an analysis of new spectroscopic observations of the bright Be star kappa Dra obtained at the Ondrejov observatory during 1992 - 2003 and UBV photometric observations se…
Spectroscopic analysis of the B/Be visual binary HR 1847
J. Kubát, S. M. Saad, A. Kawka +9
We studied both components of a slightly overlooked visual binary HR 1847 spectroscopically to determine its basic physical and orbital parameters. Basic stellar parameters were de…
Stellar Wind Variations During the X-ray High and Low States of Cygnus X-1
D. R. Gies, C. T. Bolton, R. M. Blake +10
We present results from Hubble Space Telescope UV spectroscopy of the massive X-ray binary system, HD226868 = Cyg X-1. The spectra were obtained at both orbital conjunction phases…
Fourier Disentangling Using the Technology of Virtual Observatory
P. Skoda, P. Hadrava
The Virtual Observatory is a new technology of the astronomical research allowing the seamless processing and analysis of a heterogeneous data obtained from a number of distributed…
MWC656: A Be+BH or a Be+sdO?
Th. Rivinius, R. Klement, S. D. Chojnowski +3
MWC656 has been reported as classical Be star with a black hole companion. Revisited spectral variability properties render this unlikely, with a hot subdwarf more probable.
New insights on the massive interacting binary UU Cassiopeiae
R. E. Mennickent, G. DjuraÅ¡eviÄ, I. Vince +7
We present the results of the study of the close binary UU Cassiopeiae based on previously published multi wavelength photometric and spectroscopic data. Based on eclipse timings o…
Disentangling of spectra - theory and practice
P. Hadrava
In this document a review of the author's method of Fourier disentangling of spectra of binary and multiple stars is presented for the purpose of the summer school organized at Ond…