TOI-132 b: A short-period planet in the Neptune desert transiting a $V=11.3$ G-type star

Abstract

The Neptune desert is a feature seen in the radius-mass-period plane, whereby a notable dearth of short period, Neptune-like planets is found. Here we report the {\it TESS} discovery of a new short-period planet in the Neptune desert, orbiting the G-type dwarf TYC\,8003-1117-1 (TOI-132). {\it TESS} photometry shows transit-like dips at the level of $\sim$1400 ppm occurring every $\sim$2.11 days. High-precision radial velocity follow-up with HARPS confirmed the planetary nature of the transit signal and provided a semi-amplitude radial velocity variation of $\sim$11.5 m s${}^{-1}$, which, when combined with the stellar mass of $0.97\pm 0.06$ $M_{\odot }$, provides a planetary mass of 22.83${}_{-1.80}^{+1.81}$ $M_{\oplus }$. Modeling the {\it TESS} high-quality light curve returns a planet radius of 3.43${}_{-0.14}^{+0.13}$ $R_{\oplus }$, and therefore the planet bulk density is found to be 3.11${}_{-0.450}^{+0.44}$ g cm${}^{-3}$. Planet structure models suggest that the bulk of the planet mass is in the form of a rocky core, with an atmospheric mass fraction of 4.3${}_{-2.3}^{+1.2}$\%. TOI-132 b is a {\it TESS} Level 1 Science Requirement candidate, and therefore priority follow-up will allow the search for additional planets in the system, whilst helping to constrain low-mass planet formation and evolution models, particularly valuable for better understanding the Neptune desert.

12 pages, 10 figures, 4 tables. Submitted to MNRAS. Comments welcome. Missing labels, Typos fixed

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