U B V absolute CCD photometry and differential astrometry of a sample of visual double stars with A-type primaries ^*,**

¹ Royal Belgian Observatory, Ringlaan 3, B-1180 Brussels, Belgium
² Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow 119899, Russia
³ European Southern Observatory, La Silla, Chile

Send offprint request to: N. Shatsky

Received: 4 January 1999
Accepted: 5 May 1999

Abstract

We present V magnitudes, and colours of the components of 111 visual double stars and their relative position measurements ρ and θ. The primaries are of spectral class A; the angular separation is in the range. The observations were made at the 61-cm reflector of University of Toronto Southern Observatory, Chile. The obtained photometric results are of a moderate quality for absolute values ( (mag) in V and about in the and colour indices) and more precise in and , ( and , respectively). We find that about 60% of secondaries are also of spectral type A; 56% of pairs have less than . The two-colour diagram reveals significant offset of objects from the curve of unreddened Main Sequence stars. A comprehensive survey of stars in the close vicinity to the objects is also presented. The final astrometric accuracy of in ρ and in θ provides additional measurements for study of relative motion of the components.