High-resolution Hα spectroscopy of the bright RS CVn system HR 7275.

Abstract

HR 7275 is a bright, long-period (28 day), single-lined RS CVn binary. High-resolution (0.36 A) and good signal-to-noise ratio echelle spectra do not show any clear evidence of the secondary in the system on spectral lines. Also, absence of a continuum on a low-resolution UV spectrum (IUE merged log) and the known mass function imply a main-sequence secondary with a spectral type late F to middle G, corresponding to the mass range of M2 of between 0.9 and 1.1 solar masses. The present spectra show variable H-alpha from the primary (K 1 III-IV). At least 30 percent excess emission with respect to Arcturus and about 7 percent modulation of the central intensity in the term of continuum at H-alpha has been measured. The maximum emission occurred during light minimum on the light curve of the same cycle of present observations.