J. Horn

Photometric Characteristics of the Be Stars: Almost Twenty Years of UBV Monitoring at the Hvar Observatory

Since their discovery (by Father Secchi in 1866) until the end of sixties, Be stars were not a subject of any systematic studies of their possible light and colour variations. Already at that time, the astronomical literature contained ample evidence showing that a number of Be stars were light variables. However, almost all such findings resulted as by-products of studies of different or wider groups of objects. Feinstein (1968) was probably the first who pointed out explicitly that many Be stars are light variables. A pioneering study which was aimed at the detection of light variations of a large group of Be stars by means of differential photoelectric photometry was carried out by Haupt & Schroll (1974).

KX Andromedae: Possibly a Strongly Interacting Binary

Although KX And (HD 218393, MWC 397) has been observed since the beginning of our century, we have no reliable model of this peculiar emission-line object. Published papers (e.g. Plavec et al. 1982; Kriz and Harmanec 1975 and references therein) indicate that it is a B+K W Ser-type binary with a period of 38.9 days. This paper presents a summary of intensive observations carried out during the last fifteen years. The observational material used consists of 65 coude spectra obtained with the Ondrejov 2-m telescope, UBV photometry obtained at Hvar Observatory and 28 archival IUE images. The radial-velocity and photometric data are combined with those found in the literature. A PDM period search over the interval 1 to 1000 days unambiguously indicates the 38.9-day period both in RV and photometric data. A formal orbital solution for all the optical metallic RVs leads to the following linear ephemeris for the epochs of maximum velocity: