Abstract Title: *
Doppler imaging and activity evolution of the Hertzsprung gap star OU Andromedae

Authors: *
U. Wolter, A. Borisova, R. Konstantinova-Antova, K.P. Schröder

Institution: *
Hamburger Sternwarte

Preferred format: *
Oral

Abstract Text: *
OU And is a moderately fast rotating G-type giant star, located in the Hertzsprung gap. All
Doppler images of OU And created so far show a polar spot, which thus appears to be stable at
least on the timescale of several years. In combination with evolutionary models, this suggests
that OU And has been an Ap-star during its main sequence phase. Using high-resolution
spectra from two sites (NARVAL and TIGRE), we create photospheric Doppler images and
additionally analyze the evolution of OU And’s chromospheric emission. Our data cover the
years 2008 to 2015. Combining our results with findings of earlier photometric campaigns, we
summarize that the activity of OU And has changed from a few epochs of obvious rotational
modulation in the 1980s and 90s to several later epochs without any significant modulation.