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

The Neptune desert is a feature seen in the radius-period plane, whereby a notable dearth of short period, Neptune-like planets is found. Here we report the TESS discovery of a new short-period planet in the Neptune desert, orbiting the G-type dwarf TYC 8003-1117-1 (TOI-132). TESS photometry shows transit-like dips at the level of 1400 ppm occurring every 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 11.38+0.84-0.85 m s-1, which, when combined with the stellar mass of 0.97 ± 0.06 M☉, provides a planetary mass of 22.40+1.90-1.92 M⊕. Modeling the TESS light curve returns a planet radius of 3.42+0.13-0.14 R⊕, and therefore the planet bulk density is found to be 3.08+0.44-0.46 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+1.2-2.3 per cent. TOI-132 b is a 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.