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First identification and absolute magnitudes of the red clump stars in the Solar neighbourhood for WISE
Bilir, S.; Ak, T.; Karaali, S. +4 more
We present the first determination of absolute magnitudes for the red clump (RC) stars with the Wide-field Infrared Survey Explorer (WISE). We used recently reduced parallaxes taken from the Hipparcos catalogue and identified 3889 RC stars with the WISE photometry in the Solar neighbourhood. Mode values estimated from the distributions of absolute…
The X-ray under-luminosity of the O-type supergiants HD 16691 and HD 14947 revealed by XMM-Newton
De Becker, M.
The members of the scarce category of Of+ supergiants present properties that are intermediate between regular O-stars and Wolf-Rayet (WR) stars. Significant similarities between these transitional stars and WN-type objects are now clearly established, at least in the visible and near-infrared domains, pointing to common stellar wind pr…
An XMM-Newton view of the M 17 nebula
Mernier, F.; Rauw, G.
We present the analysis of an XMM-Newton observation of the M 17 nebula. The X-ray point source population consists of massive O-type stars and a population of probable low-mass pre-main sequence stars. CEN 1a,b and OI 352, the X-ray brightest O-type stars in M 17, display hard spectra (kT of 3.8 and 2.6 keV) consistent with a colliding wind origi…
Spectroscopic observations of the interacting massive binary AQ Cassiopea
Ibanoglu, C.; Çakırlı, Ö.; Sipahi, E.
New spectroscopic observations of the double-lined eclipsing binary AQ Cas are presented. All available spectroscopic and photometric observations have been analysed for the fundamental properties of the components. Analyses show that the system consists of a massive primary with a mass of 17.63 ± 0.91 M⊙ and radius of 13.48 ± 0.64 R
Study of the late nitrogen-sequence Galactic Wolf-Rayet star WR156. Spectropolarimetry and modeling
Afanasiev, V. L.; Panchuk, V. E.; Maryeva, O. V.
For the first time spectropolarimetric observations of Wolf-Rayet star WR156 (WN8h sub-class) were conducted. Medium resolution spectropolarimetric data in the range of 3500-7200 ÅÅ were obtained at 6-m BTA telescope of Special Astrophysical Observatory RAS (SAO RAS) using recently commissioned SCORPIO-2 spectrograph. These data show that the ligh…
Elemental abundances of the supergiant stars σ Cygnus and η Leonis
Tanrıverdi, Taner
This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and the early A-type supergiant η Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and sign…
Preliminary results of the spectral analysis of Suzaku data of SW Ursae Majoris and BZ Ursae Majoris
Gök, F.; İkis Gün, G.; Karagül, A.
Herein, we present the preliminary results of the spectral analysis of the Suzaku data of SW Ursae Majoris (SW UMa) and BZ Ursae Majoris (BZ UMa) which were obtained in their quiescent states. The aim of this study was to analyse 0.5-6.0 keV energy range X-ray photons of the Suzaku satellite and to determine their emission mechanisms and the areas…