TOI-7166 b: A Habitable Zone mini-Neptune planet around a nearby low-mass star

TL;DR

The paper reports the discovery and validation of TOI-7166b, a mini-Neptune near the habitable zone of a nearby low-mass star, highlighting its potential for atmospheric characterization and follow-up studies.

Contribution

This work presents the first validation of a habitable-zone mini-Neptune around a nearby M-dwarf using combined photometric, spectroscopic, and imaging data.

Findings

TOI-7166b has a radius of 2.01 Earth radii.

The planet orbits at 12.9 days, near the habitable zone.

The host star is a nearby M4 dwarf at 35 parsecs.

Abstract

We present the discovery and validation of TOI-7166b, a 2.01+/-0.05R_Earth planet orbiting a nearby low-mass star. We validated the planet by combining TESS and multi-color high-precision photometric observations from ground-based telescopes, together with spectroscopic data, high-contrast imaging, archival images, and statistical arguments. The host star is an M4-type dwarf at a distance of ~35 pc from the Sun. It has a mass and a radius of Ms=0.190+/-0.004M_Sun and Rs=0.222+/-0.005R_Sun, respectively. TOI-7166b has an orbital period of 12.9 days, which places it close to the inner edge of the Habitable Zone of its host star, receiving an insolation flux of Sp=1.07+/-0.08S_Earth and an equilibrium temperature of Teq=249+/-5K (assuming a null Bond albedo). The brightness of the host star makes TOI-7166 a suitable target for radial velocity follow-up to measure the planetary mass and bulk density. Moreover, the physical parameters of the system including the infrared brightness (Kmag = 10.6) of the star and the planet-to-star radius ratio (0.0823+/-0.0012) make TOI-7166b an exquisite target for transmission spectroscopic observations with the JWST, to constrain the exoplanet atmospheric compositions.