Ellipsoidal primary of the RS CVn binary zeta And: Investigation using high-resolution spectroscopy and optical interferometry

Abstract

We have obtained high-resolution spectroscopy, optical interferometry, and long-term broad band photometry of the ellipsoidal primary of the RS CVn-type binary system zeta And. Based on the optical interferometry the apparent limb darkened diameter of zeta And is 2.55 +/- 0.09 mas using a uniform disk fit. The Hipparcos distance and the limb-darkened diameter obtained with a uniform disk fit give stellar radius of 15.9 +/- 0.8 Rsolar, and combined with bolometric luminosity, it implies an effective temperature of 4665 +/- 140 K. The temperature maps obtained from high resolution spectra using Doppler imaging show a strong belt of equatorial spots and hints of a cool polar cap. The equatorial spots show a concentration around the phase 0.75. This spot configuration is reminiscent of the one seen in the earlier published temperature maps of zeta And. Investigation of the Halpha line reveals both prominences and cool clouds in the chromosphere. Long-term photometry spanning 12 years shows hints of a spot activity cycle, which is also implied by the Doppler images, but the cycle length cannot be reliably determined from the current data.

9 pages, 9 figures, accepted for A&A

References in corpus (5)

• Interferometric data reduction with AMBER/VLTI.Principle,estimators and illustration
• Multiple and changing cycles of active stars II. Results
• The spin-orbit alignment of the Fomalhaut planetary system probed by optical long baseline interferometry
• J, H, K spectro-interferometry of the Mira variable S Orionis
• "Advanced" data reduction for the AMBER instrument

Cited by in corpus (8)

• No Sun-like dynamo on the active star $\zeta$ Andromedae from starspot asymmetry
• Surface magnetism of cool stars
• Measuring differential rotation of the K-giant $\zeta$\,And
• Observing dynamos in cool stars
• Optical Spectroscopy with the Technology of Virtual Observatory
• Spotted surface structure of the active giant PZ Mon
• TYC~2990-127-1: an Algol-type SB2 binary system of subgiant and red giant with a probable ongoing mass-transfer
• 3-D reconstructions of active stars - observations