Flares, Rotation, and Planets of the AU Mic System from TESS Observations
Abstract
AU Mic is a young (~24 Myr), pre-main-sequence M dwarf star that was observed in the first month of science observations of the Transiting Exoplanet Survey Satellite (TESS) and reobserved 2 years later. This target has photometric variability from a variety of sources that is readily apparent in the TESS light curves; spots induce modulation in the light curve, flares are present throughout (manifesting as sharp rises with slow exponential decay phases), and transits of AU Mic b may be seen by eye as dips in the light curve. We present a combined analysis of both TESS Sector 1 and Sector 27 AU Mic light curves including the new 20 s cadence data from TESS Year 3. We compare flare rates between both observations and analyze the spot evolution, showing that the activity levels increase slightly from Sector 1 to Sector 27. Furthermore, the 20 s data collection allows us to detect more flares, smaller flares, and better resolve flare morphology in white light as compared to the 2 minute data collection mode. We also refine the parameters for AU Mic b by fitting three additional transits of AU Mic b from Sector 27 using a model that includes stellar activity. We show that the transits exhibit clear transit timing variations with an amplitude of ~80 s. We also detect three transits of a 2.8 R ⊕ planet, AU Mic c, which has a period of 18.86 days.
- Publication:
-
The Astronomical Journal
- Pub Date:
- April 2022
- DOI:
- 10.3847/1538-3881/ac23ca
- arXiv:
- arXiv:2109.03924
- Bibcode:
- 2022AJ....163..147G
- Keywords:
-
- Exoplanet detection methods;
- Red dwarf flare stars;
- Transit timing variation method;
- Astronomy data modeling;
- M dwarf stars;
- 489;
- 1367;
- 1710;
- 1859;
- 982;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 18 pages, 13 figures, 5 tables, accepted to AJ