Stellar Variability

TESS Stellar Variability Catalog

The periodic nature of variable stars can be used to uncover important information about their intrinsic properties. TESS observed nearly the entire sky during the primary mission, thus allowing for a large-scale study of variability. We searched for periodicity in the ~230,000 stars observed at 2-minute cadence with TESS and identified ~40,000 stars that exhibit periodic variability up to 13 days in duration. In Fetherolf et al. (2022, in prep.), we will be releasing a stellar variability catalog to the community that will aid in characterizing periodic variable stars, understanding interactions (gravitational and atmospheric) between planets and their host stars, and identifying false positives when searching for new exoplanets. In direct follow-up, Simpson et al. (2022, in prep.) investigates the properties of the subset of variable stars that are known to host exoplanets.

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Non-Synchronized Rotation in Close Eclipsing Binary

There is a well-known discrepancy between observations and theoretical models for K and M stars, in that they are observed to be larger and cooler than predicted. This discrepancy could be attributed to enhanced magnetic fields and starspot activity that block convection and, thus, causes an inflation in the stellar radius. In Fetherolf et al. (2019), we measured the properties of the KIC 8736245 eclipsing binary system using ground-based photometry from Mount Laguna Observatory and the 4-year Kepler light curve. KIC 8736245 is a circular eclipsing binary system that consists of a G-type star leaving the Main Sequence and a K-type star that are each spinning super- and sub-synchronously compared to the 5.07 day orbital period (see periodogram on the left). Overall, this system proves to be an interesting case study for the exchange of angular momentum as binary stars evolve off the Main Sequence.

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