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Astron. Astrophys. 346, 87-90 (1999)

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1. Introduction

BD+61o2213 (NGC 7160*4, ADS 15430, [FORMULA] = [FORMULA], [FORMULA] = +62o21´40") is a reddened B3 star and the fourth brigtest member of the open cluster NGC 7160. Its improved all-sky UBV magnitudes were derived by Harmanec et al. (1994):

V = 8[FORMULA]961, [FORMULA] = +0[FORMULA]191, [FORMULA] = -0.466.

Light variability of BD+61o2213 was first reported by Hill (1967a) and Hill (1967b) but no details were given; the star was tentatively classified as an eclipsing binary with the reference to its variable radial velocity - see Hayford (1932). Hill et al. (1976) published their individual observations of BD+61o2213 , secured during 1972 and 1973 in the DAO photometric system and suggested that BD+61o2213 is a light variable. Subsequently, the star was included into the catalogue of suspected variables by Kukarkin et al. (1982) as NSV 13949.

BD+61o2213 was used occasionally as one of the transformation standards during systematic observations of Be and Ap stars and some binaries at Hvar and Skalnaté Pleso Observatories - see Harmanec et al. (1994). This was not, however, listed among good standards, observed frequently enough. Recently, it was observed again as a possible transformation standard during our observations of selected binaries and early-type rapid variables at San Pedro Mártir Observatory. Preliminary reductions of these observations clearly indicated that the star is variable. It was, therefore, re-observed more systematically at Hvar. The purpose of this paper is to demonstrate the variability of the star, derive probable timescales of the variability and call attention of spectroscopists and photometrists to its further monitoring which could possibly also help to improve our knowledge of the distance of the NGC 7160 cluster.

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© European Southern Observatory (ESO) 1999

Online publication: May 6, 1999