2000A&A...357..608S

We present the first Doppler images of the newly discovered RS CVn binary HD 291095. The star is a synchronuously rotating subgiant in a 4-day spectroscopic binary with an unseen companion and is particularly interesting because it is one of the few evolved stars that show large flares. Three consecutive years of moderate-resolution KPNO spectra and continuous VI and by photometry with our APTs reveal a large, cool, and long-living asymmetric polar spot. Its temperature is approximately 1100 K below the average photospheric temperature. Several low latitude and even equatorial spots were evident at the same time. We interpret this latitudinal spot bimodality to be due to a combination of poleward meridional circulation and more frequent magnetic reconnections near the pole than near the equator. During the 1998 Doppler-imaging observations, a strong flare in Hα was detected which coincided with a meridian passage of the most asymmetric part of the polar spot. We estimate a total flare energy of 5x10³⁴ erg typical for flares on very active RS CVn systems. No photospheric heating is evident in our surface maps from optically thin spectral lines of various temperature sensitivities.