Brightness variability investigation of BD+61°154

Abstract

Photoelectrk ubvyHaHP observations of the Herbig Ae/Be star BD+61° 154 are presented. The observational data are analyzed proceeding from the simple hypothesis that the light variation is mainly due to temperature changes of gaseous envelope. amplitude of a few tenths of magnitude was discovered by Ponomareva (1975). Shevchenko (1989) had shown that light variation is quasiperiodic with the timescale within 5 -27 days and confirmed Ponomareva's conclusion that during light fading all colour indices increase or remain constant. In this paper, we are analysing the dependence of colour indices and emission line intensities on the light variation aiming to understanding what is the primary source of light variation. This investigation is a part of a long-term study of the Herbig Ae/Be stars and related objects which had been launched in -4basturnani Observatory in 1983 (Chkhikvadze and Janiashvily 1986; Chkhikvadze 1988; Chkhikvadze 1989a, 1989b). ObservationsAll On the whole for the entire season of the observations the probable errors of a single observation estimated from repeated measures of the comparison star are: y, fO"012; b , fO"013; v , fO"012; u, fO"O18; HP(narrow), fO"018; HP(wide), fO"010. The results of the observations in the instrumental system are presented in Table 1: Am is the mean (over the night) value of magnitude difference between B D + 61'154 and comparison star in corresponding filters with its standard error and N is the number of measurements over the night.