MOST Observations of the Flare Star AD Leo

We present continuous, high-precision photometric monitoring data with 1 minute cadence of the dM3e flare star AD Leo with the MOST satellite. We observed 19 flares in 5.8 days and found a flare frequency distribution that is similar to previous studies. The light curve reveals a sinusoidal modulation with a period of days that we attribute to the rotation of a stellar spot rotating into and out of view. We see no correlation between the occurrence of flares and rotational phase, indicating that there may be many spots distributed at different longitudes or, possibly, that the modulation is caused by varying surface coverage of a large polar spot that is viewed nearly pole-on. The data show no correlation between flare energy and the time since the previous flare. We use these results to reject a simple model in which all magnetic energy is stored in one active region and released only during flares.

Based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium.