TOI-532b: The Habitable-zone Planet Finder confirms a Large Super Neptune in the Neptune Desert orbiting a metal-rich M-dwarf host
Abstract
We confirm the planetary nature of TOI-532b, using a combination of precise near-infrared radial velocities with the Habitable-zone Planet Finder, Transiting Exoplanet Survey Satellite (TESS) light curves, ground-based photometric follow up, and high-contrast imaging. TOI-532 is a faint (J ~ 11.5) metal-rich M dwarf with Teff = 3957 ± 69 K and [Fe/H] = 0.38 ± 0.04; it hosts a transiting gaseous planet with a period of ~2.3 days. Joint fitting of the radial velocities with the TESS and ground-based transits reveal a planet with radius of 5.82 ± 0.19 R⊕, and a mass of ${61.5}_{-9.3}^{+9.7}$ M⊕. TOI-532b is the largest and most massive super Neptune detected around an M dwarf with both mass and radius measurements, and it bridges the gap between the Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. It also follows the previously noted trend between gas giants and host-star metallicity for M-dwarf planets. In addition, it is situated at the edge of the Neptune desert in the Radius-Insolation plane, helping place constraints on the mechanisms responsible for sculpting this region of planetary parameter space.
- Publication:
-
The Astronomical Journal
- Pub Date:
- October 2021
- DOI:
- 10.3847/1538-3881/ac1940
- arXiv:
- arXiv:2107.13670
- Bibcode:
- 2021AJ....162..135K
- Keywords:
-
- Extrasolar gaseous planets;
- Radial velocity;
- Transit photometry;
- Hot Neptunes;
- 2172;
- 1332;
- 1709;
- 754;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 19 pages, 9 figures, 4 tables. arXiv admin note: text overlap with arXiv:2006.14546