Spectral observations of flare stars in the neighborhood of the sun

Abstract

Results of spectral monitoring of the flare stars HU Del, CM Dra, WX UMa, and VW Com by the 2.6-m telescope at the Byurakan Observatory during May-June 2012 with the SCORPIO spectral camera are reported. A strong flare of WX UMa was recorded during the observation period, as well as faint flares of CM Dra and HU Del, while no variations in brightness or equivalent widths were observed for VW Com. During all the recorded flares the maximum brightness corresponded to minimum values of the equivalent widths of the Hα and Hβ emission lines. The energy distribution in the spectrum of WX UMa changed sharply during the flare. The class M6 spectrum of the star transformed into an early type B spectrum. Finally, the appearance of the forbidden oxygen [OI] 6300 A line with an intensity comparable to that of [OI] 5577 A seems to indicate simultaneous release of the energy of the flare in different layers of the chromosphere. © 2013 Springer Science+Business Media New York.