TOI-532b: The Habitable-zone Planet Finder confirms a Large Super Neptune in the Neptune Desert orbiting a metal-rich M-dwarf host

2021/07/31 by Shubham Kanodia, Gudmundur Stefansson, Guðmundur Stefánsson +37
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Computer science #Dwarf planet #Exoplanet #Gas giant #Geology #Jupiter (rocket family) #Metallicity #Neptune #Physics #Planet #RADIUS #Space exploration #Stars #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.IM

paper · pdf · doi:10.3847/1538-3881/ac1940

published as Astronomical Journal, 162, 135, 2021 · 19 pages, 9 figures, 4 tables. arXiv admin note: text overlap with arXiv:2006.14546

arxiv created 2021/09/09 · openalex publication_date 2021/09/09 · arxiv updated 2021/09/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

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 T eff = 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>61.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>9.3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>9.7</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> 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.

Citations

• TOI-1728b: The Habitable-zone Planet Finder confirms a warm super Neptune orbiting an M dwarf host
• Matplotlib: A 2D Graphics Environment
• THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE
• Models of very-low-mass stars, brown dwarfs and exoplanets
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• Correcting for the Effects of Interstellar Extinction
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
• Origins of Hot Jupiters
• BANYAN. XI. The BANYAN Σ Multivariate Bayesian Algorithm to Identify Members of Young Associations with 150 pc
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Frequency of planets orbiting M dwarfs in the Solar neighbourhood
• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Hot Jupiters: Origins, Structure, Atmospheres
• Gaia Early Data Release 3 Summary of the contents and survey properties
• UBVRI passbands