New Results of a Variability Study of Bright OB Supergiants with BRITE

Monika Rybicka, Elżbieta Zocłońska, Sanja Tomić and the BEST

The hot part of H-R diagram contains many stars that are variable. The causes are still not understood, but could be convection, stellar winds, granulation or other processes. Theoretical models predict that the origin of variability of massive stars can be pulsations, which can be excited by different mechanisms such as the kappa or epsilon mechanisms. In this paper we present results of analyses of five OB stars: 55 Cyg, HD 202850, HD 2905, HD 23180 and HD 24398. We used BRITE data and, in the case of two stars, HD 2905 and HD 202850, spectroscopic observations. We did not find evidence for pulsations for three of the stars: HD 23180, HD 24398 and HD 2905. The data for 55 Cyg show some variability, but the frequencies found by us are different from those reported in a previous study. Therefore, the star should be analyzed in more detail. Combining spectroscopy and photometry of HD 202850 allows to find one frequency F=0.265 c/d. The frequency was found separately in spectroscopy and in BRITE data, which suggests it is intrinsic to the star.

Proceedings of the Polish Astronomical Society, vol. 8, 134-138 (2018)

Download full article as PDF file: