TOI-1846b: A super-Earth in the radius valley orbiting a nearby M dwarf
Abstract
We present the discovery and validation of a super-Earth planet orbiting the M dwarf star TOI-1846 (TIC 198385543). The host star(Kmag = 9.6)is located 47 pc away and has a radius of Rs=0.41+/-0.01RSun,a mass of Ms=0.40+/-0.02MSun and an effective temperature of Teff=3568+/-44K. Our analyses are based on joint modelling of TESS photometry and ground-based multi-color photometric data. We also use high-resolution imaging and archival images, as well as statistical validation techniques to support the planetary system nature. We find that TOI-1846b is a super-Earth sized planet with radius of Rp=1.79+/-0.07REarth and a predicted mass of Mp=4.4+1.6-1.0MEarth (from the Chen & Kipping relation) on a 3.9 d orbit, with an equilibrium temperature of Teq=589+/-20K (assuming a null Bond Albedo) and an incident flux of Sp=17.6+/-2.0SEarth. Based on the two RV measurements obtained with the TRES spectrograph and high-resolution imaging, a non-planetary transiting companion is excluded. With a radius of ~1.8REarth, TOI-1846b is within the sparsely populated radius range around 2REarth known as the radius gap (or radius valley). This discovery can contribute to refining the precise location of the radius valley for small planets orbiting bright M dwarfs, thereby enhancing our understanding of planetary formation and evolution processes.
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