Variations of beta Comae through a Magnetic Minimum (original) (raw)

NASA/ADS

;

Abstract

The dwarf star β Com = HR 4983 = HD 114710 (GO V, B-V = 0.57) is close to the Sun in the H-R diagram, being only ≈260 K hotter. We present measurements done over several years of (1) the line depth ratios of V I λ6251.83 to Fe I λ6252.57 to establish the temperature, (2) the line bisectors as a measure of the star's granulation, (3) Ca II H and K emission as an indirect indicator of magnetic activity, and (4) the blue and visual magnitudes as an indication of the power output. All these parameters show a similar variation consisting of a broad minimum extending over approximately 5 years, but the minima do not occur at the same epoch. The magnetic signature leads the others in time. Time lags relative to the magnetic variation are 0.9±0.3 yr for the photometric data, 2.9±0.3 yr for the temperature, and 2.9±0.5 yr for the granulation. A 1% variation in radius during the 5 yr interval is indicated.

Publication:

The Astrophysical Journal

Pub Date:

January 1996

DOI:

10.1086/176658

Bibcode:

1996ApJ...456..365G

Keywords: