Long-term stellar activity of M dwarfs: Combining K2 and TESS

Studies of the rotation and activity of M type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution.
Using the outstanding photometric capabilities of space telescopes rotation signals even with low amplitudes can be investigated in up to now unrivaled detail. By combining data of Kepler/K2 and TESS the star spot activity of M dwarfs can be monitored on a decade timescale.
In the framework of our study on the rotation-activity relation for M dwarfs that is based on the Lepine and Gaidos (2011) catalog we also aim at an investigation of the long-term activity.
While K2 was observing fields distributed around the ecliptic plane, the TESS prime mission was oriented along a line of ecliptic longitude with one camera centered on an ecliptic pole. Due to these different observing strategies, the overlap between K2 and TESS is marginal. However, 45 stars from our sample were observed with both missions of which four targets were analyzed in more detail.
Here, I present our results of the combined K2 and TESS stellar activity studies for two targets of our sample. Furthermore, we will show that combining missions like K2 and TESS are a promising method for detecting stellar activity cycles.