0000000000310287

AUTHOR

Leonardos Gkouvelis

showing 3 related works from this author

Physical parameters of IPHAS-selected classical Be stars

2016

We present a semi-automatic procedure to obtain fundamental physical parameters and distances of classical Be (CBe) stars, based on the Barbier-Chalonge-Divan (BCD) spectrophotometric system. Our aim is to apply this procedure to a large sample of CBe stars detected by the IPHAS photometric survey, to determine their fundamental physical parameters and to explore their suitability as galactic structure tracers. In this paper we describe the methodology used and the validation of the procedure by comparing our results with those obtained from different independent astrophysical techniques for subsamples of stars in common with other studies. We also present a test case study of the galactic …

Physics010504 meteorology & atmospheric sciencesFOS: Physical sciencesAstronomy and AstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysics01 natural sciencesStarsAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary Science0103 physical sciencesAstrophysics::Solar and Stellar Astrophysics010303 astronomy & astrophysicsAstrophysics::Galaxy AstrophysicsSolar and Stellar Astrophysics (astro-ph.SR)0105 earth and related environmental sciencesAstronomy & Astrophysics
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Long-term optical variability of high-mass X-ray binaries. II. Spectroscopy

2016

We present the results of our monitoring program to study the long-term variability of the Halpha line in high-mass X-ray binaries. We have carried out the most complete optical spectroscopic study of the global properties of high-mass X-ray binaries so far with the analysis of more than 1100 spectra of 20 sources. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. Our results can be summarised as follows: i) we find that Be/X-ray binaries with narrow orbits are more variable than systems with long orbital periods, ii) we show that a Keplerian distribution of the gas particles provides a good descripti…

Be starAstrophysics::High Energy Astrophysical PhenomenaFOS: Physical sciencesAstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsCompact star01 natural sciences0103 physical sciencesAstrophysics::Solar and Stellar Astrophysics010303 astronomy & astrophysicsAstrophysics::Galaxy AstrophysicsSolar and Stellar Astrophysics (astro-ph.SR)PhysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)010308 nuclear & particles physicsAstronomy and AstrophysicsMonitoring programAccretion (astrophysics)StarsNeutron starAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceAstrophysics::Earth and Planetary AstrophysicsSupergiantAstrophysics - High Energy Astrophysical PhenomenaEquivalent width
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Spectral classification & physical parameters of the IPHAS CBe stars in the BCD system.

2017

The INT Photometric Hα Survey (IPHAS) has detected tens of thousands of emission line objects in the Northern Galactic Plane. Spectroscopic follow-up has shown that the vast majority of them are Classical Be (CBe) stars, rapidly rotat- ing main sequence B type stars which develop an outflowing circumstellar disk by mechanisms not yet completely understood. In this work we present a study of the full catalogue of the CBe stars discovered by IPHAS. We have analyzed 805 low resolution spectra of 732 IPHAS CBe stars. With a semi-automatic proce- dure, which we evaluate at the first part of this work, we obtained the relevant physical parameters, including the effective temperature, surface grav…

UNESCO::ASTRONOMÍA Y ASTROFÍSICA:ASTRONOMÍA Y ASTROFÍSICA [UNESCO]Be stars rotationa velocities circumstellar disc galactic structure
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