Stellar activity from observations with the KEPLER space telescope: The M dwarf GJ 1243

We used continuous observations with the KEPLER space telescope during 44.45 days to study the activity of the fully convective low-mass M dwarf GJ 1243. The star’s rotational period is 0.593 days. Our precision photometry of GJ 1243 made it possible to study its surface temperature inhomogeneities and follow their evolution. We find evidence for two active longitudes on the surface of the star, separated by 203° in longitude or 0.56 in phase. The position of spots on the surface was found to be very stable during the analyzed 74 rotation periods. Assuming that the rotational axis is inclined to the line of sight by i = 60°, the total spotted area S is, on average, 3.2% of the total visible stellar surface, and increased by 0.7% in 100 days; if i = 30°, the area is S = 5.6%. The change in S is due to an increase in the area of the smaller active region. We compare the magnetic-activity features of GJ 1243 and another fully convective star, V374 Peg.