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Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ∼55000 stars and mean radial velocities of 516 Galactic open clusters and associations
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V. +2 more
We present the 2nd version of the Catalogue of Radial Velocities with Astrometric Data (CRVAD-2). This is the result of the cross-identification of stars from the All-Sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5) with the General Catalogue of Radial Velocities and with other recently published radial velocity lists and catalogues. The CRV…
Evolution of magnetic fields in stars across the upper main sequence: II. Observed distribution of the magnetic field geometry
Hubrig, S.; North, P.; Schöller, M.
We re-discuss the evolutionary state of upper main sequence magnetic stars using a sample of Ap and Bp stars with accurate Hipparcos parallaxes and definitely determined longitudinal magnetic fields. We confirm our previous results obtained from the study of Ap and Bp stars with accurate measurements of the mean magnetic field modulus and mean qua…
Estimation of galactic model parameters with the Sloan Digital Sky Survey and the metallicity distribution in two fields in the anti-centre direction of the Galaxy
Bilir, S.; Karaali, S.; Buser, R. +1 more
We estimated the galactic model parameters from the Sloan Digital Sky Survey (SDSS) data reduced for two fields in the anti-centre direction of the Galaxy, l= 180{o}, and symmetric relative to the galactic plane, b=+45{o} (north field) and b=-45{o} (south field). The large size of each field, 60 deg2, an…
Combining astrometry with the light-time effect: The case of VW Cep, ζ Phe and HT Vir
Wolf, M.; Zasche, P.
Three eclipsing binary systems with astrometric orbit have been studied. For a detailed analysis two circular-orbit binaries (VW Cep and HT Vir) and one binary with an eccentric orbit (ζ Phe) have been chosen. Merging together astrometry and the analysis of the times of minima, one is able to describe the orbit of such a system completely. The O-C…
Preliminary results on the fundamental parameters of the eclipsing binary V398 Lacertae
Frasca, A.; Soydugan, F.; Çakırlı, Ö. +2 more
The Hipparcos Space Astrometry Mission photometric observations of V398 Lac, led to the discovery of its variability, allowing to classify it as an eclipsing binary with an orbital period of about 5.4 days. This prompted us to acquire high-resolution échelle spectra with the aim of performing accurate radial velocity measurements and to determine …
Variability and evolution in various classes of post-AGB stars
Jeffery, C. S.; Şahin, T.
We aim to compare properties of early-type post-asymptotic giant-branch (post-AGB) stars, including normal first-time B-type post-AGB stars, and extreme helium stars (EHes). Hipparcos photometry for 12 post-AGB stars and 7 EHe stars has been analyzed; 5 post-AGB stars are clearly variable. The Hipparcos data are not sufficiently sensitive to detec…
U BV photoelectric photometry of the 1H/2H double mode cepheid CO Aurigae
Santangelo, M. M. M.; Cavalletti, G.; Benedetti, W.
We performed new U BV photoelectric photometry of the double mode cepheid CO Aur. A careful time series analysis, by means of various algorithms, of our light curves of CO Aur enabled us to confirm the two previously known periodicities (Antonello et al. 1986) and their ratio of about 0.800. This ratio can be explained if CO Aur is a double mode c…