Abstract
Proxima Centauri is our nearest stellar neighbor and one of the most
well-studied stars in the sky. In 2016, a planetary companion was detected
through radial velocity measurements. Proxima Centauri b has a minimum mass of
1.3 Earth masses and orbits with a period of 11.2 days at 0.05 AU from its
stellar host, and resides within the star's Habitable Zone. While recent work
has shown that Proxima Centauri b likely does not transit, given the value of
potential atmospheric observations via transmission spectroscopy of the closest
possible Habitable Zone planet, we reevaluate the possibility that Proxima
Centauri b is a transiting exoplanet using data from the Transiting Exoplanet
Survey Satellite (TESS). We use three sectors (Sectors 11, 12, and 38 at
2-minute cadence) of observations from TESS to search for planets. Proxima
Centauri is an extremely active M5.5 star, emitting frequent white-light
flares; we employ a novel method that includes modeling the stellar activity in
our planet search algorithm. We do not detect any planet signals. We injected
synthetic transiting planets into the TESS and use this analysis to show that
Proxima Centauri b cannot be a transiting exoplanet with a radius larger than
0.4 R$_øplus$. Moreover, we show that it is unlikely that any Habitable Zone
planets larger than Mars transit Proxima Centauri.
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