${UBV}$ absolute CCD photometry and differential astrometry of close visual double stars, with G-type primaries

Abstract

Abstract. We present V magnitudes, (B − V ) and (U − B) colours of close visual double star components, and their differences as well as separations and position angles of 40 visual double stars. The common properties of the members of this sample are the small angular separation ρ, which is less than 7 , and the common spectral type of the primaries, which are of G-type. The observations made with the Bessel U , B and V filters, while the astrometry was performed in the V filter only. For the observations, the CCD camera attached to the Cassegrain focus of the 90 cm Dutch telescope, at La Silla, Chile, had been used. From the analysis of the data we concluded that from the sample of the fourty double stars observed seven proved to be physical pairs, while the rest must have common origin components.

Fast-rotating nearby solar-type stars

“…We obtained separate spectra for the two components; the South-West brighter component (A) is an SB1 for which we detected Ca II K emission, the North-East fainter component (B) is an SB2 (M Va = 6.62, M Vb = 7.11). Nakos et al (1997) this photometry is quite different from the values reported in the Hipparcos catalogue, but agrees well with our results. Soderblom et al (1998) (Henry et al 1995) already studied by our group (Cutispoto et al 1999).…”

High-Resolution Spectroscopy of Some Very Active Southern Stars

“…No high-energy satellite detections of these stars have been reported. The accurate CCD-based(B − V ) values ofNakos et al (1997) for each component represent a substantial improvement over the uncertain composite color tabulated in Paper I. However, the true colors of these stars are uncertain.…”