A Super-Earth near the HZ of Ross 508

Subject: A Super-Earth near the HZ of Ross 508 25th May 2022, 3:45 am

Quote :: We report the near-infrared radial-velocity (RV) discovery of a super-Earth planet on a 10.77-day orbit around the M4.5 dwarf Ross 508 (Jmag=9.1). Using precision RVs from the Subaru Telescope IRD (InfraRed Doppler) instrument, we derive a semi-amplitude of 3.92+0.60−0.58 ms−1, corresponding to a planet with a minimum mass msini=4.00+0.53−0.55 M⊕. We find no evidence of significant signals at the detected period in spectroscopic stellar activity indicators or MEarth photometry. The planet, Ross 508 b, has a semimajor-axis of 0.05366+0.00056−0.00049 au. This gives an orbit-averaged insolation of ≈1.4 times the Earth's value, placing Ross 508 b near the inner edge of its star's habitable zone. We have explored the possibility that the planet has a high eccentricity and its host is accompanied by an additional unconfirmed companion on a wide orbit. Our discovery demonstrates that the near-infrared RV search can play a crucial role to find a low-mass planet around cool M dwarfs like Ross 508.