Kavli Affiliate: Roland K. Vanderspek
| First 5 Authors: Emily A. Gilbert, Thomas Barclay, Elisa V. Quintana, Lucianne M. Walkowicz, Laura D. Vega
| Summary:
AU Mic is a young ($sim$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 re-observed two 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-second 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-second 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 (TTVs) with an amplitude of $sim$80 seconds. We also detect
three transits of a 2.8 $R_oplus$ planet, AU Mic c, which has a period of
18.86 days.
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