Flares, Rotation, and Planets of the AU Mic System from TESS Observations

April 2022 • 2022AJ....163..147G

Authors • Gilbert, Emily A. • Barclay, Thomas • Quintana, Elisa V. • Walkowicz, Lucianne M. • Vega, Laura D. • Schlieder, Joshua E. • Monsue, Teresa • Cale, Bryson L. • Collins, Kevin I. • Gaidos, Eric • El Mufti, Mohammed • Reefe, Michael A. • Plavchan, Peter • Tanner, Angelle • Wittenmyer, Robert A. • Wittrock, Justin M. • Jenkins, Jon M. • Latham, David W. • Ricker, George R. • Rose, Mark E. • Seager, S. • Vanderspek, Roland K. • Winn, Joshua N.

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.

Links

• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2022AJ....163..147G
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ac23ca/pdf
• PREPRINT http://arxiv.org/abs/2109.03924
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2022AJ....163..147G
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2022AJ....163..147G
• ELECTR https://doi.org/10.3847/1538-3881/ac23ca