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Title: The Directly Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator

51 Eri is well known for hosting a directly imaged giant planet and for its membership to theβPictoris moving group. Using 2 minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS), we detect multiperiodic variability in 51 Eri that is consistent with pulsations of Gamma Doradus (γDor) stars. We identify the most significant pulsation modes (with frequencies between ∼0.5 and 3.9 cycles day−1and amplitudes ranging between ∼1 and 2 mmag) as dipole and quadrupole gravity modes, as well as Rossby modes, as previously observed in KeplerγDor stars. Our results demonstrate that previously reported variability attributed to stellar rotation is instead likely due toγDor pulsations. Using the mean frequency of the= 1 gravity modes, together with empirical trends of the KeplerγDor population, we estimate a plausible stellar core rotation period of0.90.1+0.3days for 51 Eri. We find no significant evidence for transiting companions around 51 Eri in the residual light curve. The detection ofγDor pulsations presented here, together with follow-up observations and modeling, may enable the determination of an asteroseismic age for this benchmark system. Future TESS observations would allow a constraint on the stellar core rotation rate, which in turn traces the surface rotation rate, and thus would help clarify whether or not the stellar equatorial plane and orbit of 51 Eri b are coplanar.

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Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Page Range / eLocation ID:
Article No. 49
Medium: X
Sponsoring Org:
National Science Foundation
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