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Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos II. Preliminary orbits for six astrometric binaries

Gontcharov, G. A.; Kiyaeva, O. V.

Based on a direct combination of the Hipparcos data with astrometric ground-based observational catalogues having epochs between 1938 and 1999 the preliminary orbits and component masses are calculated for six binaries with no previous orbit calculation: ι Vir (HIP 69701) with period of 55 years, photocentric semi-major axis of 200 mas, relative s…

New intrinsic-colour calibration for uvby- β photometry

Karataş, Yüksel; Schuster, William J.

A new intrinsic-colour calibration ((b-y)_o-β) is presented for the uvby- β photometric system, making use of re-calibrated Hipparcos parallaxes and published reddening maps. This new calibration for (b-y)_o-β, our Eq. (1), has been based upon stars with d_Hip<70pc in the photometric catalogues of Schuster and Niss…

Absolute parameters of the newly-identified contact binary star IS Canis Major

Özkardeş, B.; Erdem, A.

This paper presents the results of the first high-resolution spectroscopic observations of the Southern W UMa type system IS CMa. Spectroscopic observations of the system were made at Mt. John University Observatory using a HERCULES fibre-fed échelle spectrograph in September 2007. The first radial velocities of the component stars of the system w…

Is NP Aqr a new near-contact binary?

Çakırlı, Ö.; İbanoǧlu, C.; Dervişoǧlu, A.

We present radial velocities of the double-lined spectroscopic binary NP Aqr. The radial velocities and the optical light curves obtained by Hipparcos and ASAS-3 are analyzed separately. The masses of the primary and secondary components have been found to be 1.65±0.09 and 0.99±0.05M_⊙, respectively. The cross-correlation functions indic…