Two super-Earths at the edge of the habitable zone of the nearby M dwarf TOI-2095

Abstract

The main scientific goal of TESS is to find planets smaller than Neptune around stars bright enough to allow further characterization studies. Given our current instrumentation and detection biases, M dwarfs are prime targets to search for small planets that are in (or nearby) the habitable zone of their host star. Here we use photometric observations and CARMENES radial velocity measurements to validate a pair of transiting planet candidates found by TESS. The data was fitted simultaneously using a Bayesian MCMC procedure taking into account the stellar variability present in the photometric and spectroscopic time series. We confirm the planetary origin of the two transiting candidates orbiting around TOI-2095 (TIC 235678745). The star is a nearby M dwarf ($d = 41.90 \pm 0.03$ pc, $T_{\rm eff} = 3759 \pm 87$ K, $V = 12.6$ mag) with a stellar mass and radius of $M_\star = 0.44 \pm 0.02 \; M_\odot$ and $R_\star = 0.44 \pm 0.02 \; R_\odot$, respectively. The planetary system is composed of two transiting planets: TOI-2095b with an orbital period of $P_b = 17.66484 \pm (7\times 10^{-5})$ days and TOI-2095c with $P_c = 28.17232 \pm (14\times 10^{-5})$ days. Both planets have similar sizes with $R_b = 1.25 \pm 0.07 \; R_\oplus$ and $R_c = 1.33 \pm 0.08 \; R_\oplus$ for planet b and c, respectively. We put upper limits on the masses of these objects with $M_b < 4.1 \; M_\oplus$ for the inner and $M_c < 7.4 \; M_\oplus$ for the outer planet (95\% confidence level). These two planets present equilibrium temperatures in the range of 300 - 350 K and are close to the inner edge of the habitable zone of their star.Comment: Submitted to Astronomy & Astrophysic