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One of the main goals of the NASA's TESS (Transiting Exoplanet Survey Satellite) mission is the discovery of Earth-like planets around nearby M-dwarf stars. Here, we present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M-dwarfs: TOI- 5720b, TOI-6008b and TOI-6086b. We combined TESS data, ground-based multi-color light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD RVs data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720b is a planet with a radius of Rp=1. 09 Re orbiting a nearby (23 pc) M2. 5 host, with an orbital period of P=1. 43 days. It has an equilibrium temperature of Teq=708 K and an incident flux of Sp=41. 7 Se. TOI-6008b has a period of P=0. 86 day, a radius of Rp=1. 03 Re, an equilibrium temperature of Teq=707 K and an incident flux of Sp=41. 5 Se. The host star (TOI-6008) is a nearby (36 pc) M5 with an effective temperature of Teff=3075 K. Based on the RV measurements collected with Subaru/IRD, we set a 3-sigma upper limit of Mp<4 MEarth, thus ruling out a star or brown dwarf as the transiting companion. TOI-6086b orbits its nearby (31 pc) M3 host star (Teff=3200 K) every 1. 39 days, and has a radius of Rp=1. 18 Re, an equilibrium temperature of Teq=634 K and an incident flux of Sp=26. 8 Se. Additional high precision radial velocity measurements are needed to derive the planetary masses and bulk densities, and to search for additional planets in the systems. Moreover, short-period earth-sized planets orbiting around nearby M-dwarfs are suitable targets for atmospheric characterization with the James Webb Space Telescope (JWST) through transmission and emission spectroscopy, and phase curve photometry.
Barkaoui et al. (Fri,) studied this question.