Surface velocity network with anti-solar differential rotation on the active K-giant $\sigma$ Geminorum

Abstract

We demonstrate the power of the local correlation tracking technique on stellar data for the first time. We recover the spot migration pattern of the long-period RS CVn-type binary $\sigma$ Gem from a set of six Doppler images from 3.6 consecutive rotation cycles. The resulting surface flow map suggests a weak anti-solar differential rotation with $\alpha \approx -0.0022\pm 0.0016$, and a coherent poleward spot migration with an average velocity of $220\pm 10$ m s${}^{-1}$. This result agrees with our recent findings from another study and could also be confirmed theoretically.

3 pages, 3 figures, conference title: 5th Potsdam Thinkshop, accepted for publication in Astronomische Nachrichten

References in corpus (1)

• Large-scale horizontal flows in the solar photosphere I: Method and tests on synthetic data

Cited by in corpus (5)

• Imaging starspot evolution on Kepler target KIC 5110407 using light curve inversion
• Antisolar differential rotation of the K1-giant sigma Geminorum revisited
• Observing dynamos in cool stars
• Spot activity of the RS CVn star σ Geminorum
• Impact of anti-solar differential rotation in mean-field solar-type dynamos -- Exploring possible magnetic cycles in slowly rotating stars