Temperate super-Earth found orbiting nearby red dwarf Ross 318

Ross 318 (Gliese 48) is a red dwarf star with strong magnetic activity and a rotation period of about fifty-one and a half days. Researchers analyzed over a decade of radial velocity data from CARMENES and HIRES, along with TESS space telescope observations, to search for planets around this star. They discovered a planet, Ross 318 b (Gliese 48 b), which has a minimum mass about six times that of Earth and orbits the star every thirty-nine days. The planet's signal was confirmed by its consistency over fifteen years and by being present in both visible and near-infrared data.

TESS photometry did not detect a transit for Ross 318 b, and further tests showed that if the planet did transit, it would have been seen. This means the planet's orbit is not aligned to pass in front of the star from our viewpoint. The planet receives about fifty-eight percent of the sunlight that Earth gets and is located in the star's conservative habitable zone, making it a promising candidate for further study of temperate super-Earths around red dwarfs.

The study demonstrates the power of combining different observation methods to confirm the existence and properties of planets around active stars. Ross 318 b stands out as one of the most interesting temperate super-Earths found around a red dwarf so far.

Key findings
- Ross 318 b is a super-Earth with a minimum mass of 6.2 Earth masses.
- The planet orbits a red dwarf every 39.6 days and does not transit the star.
- Ross 318 b is located in the conservative habitable zone.
- The planet's signal is confirmed by long-term and multi-wavelength data.
- The study rules out a transiting geometry with high confidence.

Scientific study

Detection and Characterization of the Temperate Super-Earth Ross 318 b (external link)