CCD astrometry and UBV photometry of visual binaries

Abstract

Abstract. Differences ∆V of magnitude and ∆(B−V ) and ∆(U −B) colours, as well as separations and position angles of 42 relatively close double stars are presented. The selection criteria of our sample are: the relatively small separation (between 2.5 and 5 arcseconds), magnitude difference under 1.25 mag, and mainly G-type primaries. The CCD observations, performed at the 90 cm Dutch telescope at ESO, were made using the Bessel U , B and V filters; the astrometry was done in the V filter only.From the analysis of the photometric data we conclude that 16 binaries in our sample have components with practically the same T eff , since they have almost the same colours; one binary has components with identical characteristics. We also note the good internal accuracy of the astrometric CCD measurements.

Orbital Elements of visual binary stars with very short arcs: With application to double stars from the 1829 southern double star catalog of James Dunlop

“…Column 2 contains the WDS system identifier, underneath which is the Discoverer code of the particular double star (from the WDS). All physical separations are less than 1 pc (Dommanget 1967 and Sinachopoulos 1991 had a separation limit of 0.01 pc, recently others have demonstrated a limit approaching 1 pc, Longhitano & Binggeli 2010, others to the galactic tidal limit of ∼1.7 pc for solar type stars, Halbwachs et al 2012; Moeckel & Bate 2010), and each of the eight also exhibit a common proper motion (following Hartkopf et al 2013), justifying their inclusion as possible binary double stars.…”

Pulsational properties of ten new slowly pulsating B stars

“…HD 86424: This star is a visual binary with a magnitude difference of the components (HD 86424 and CD−41 5479B) of 2.3 mag and a separation of 9 . 7 (Sinachopoulos 1988). Using the available Gaia DR2 parallaxes, Bailer-Jones et al (2018) estimate distances between 547 and 573 pc for HD 86424 and 585 and 607 pc for CD−41 5479B.…”

The Dependence of the Evolution of Early‐Type Galaxies on Their Environment

“…They are defined in such a way to yield zero colour terms for an A0V star spectrum in all passbands. To calibrate the FORS filter system, the A0V spectrum from Pickles (1998) was used and the finetuning of the respective factors C X was performed with the equations given in Sinachopoulos & van Dessel (1998). Finally, the constant C sys for transformations between the FORS and the Johnson system was calculated from the colour (V fors − V J ) (ibid.).…”