TOI-270: A Nearby Red Dwarf with Three Small Worlds

TOI-270 is an M-type star 73.3 light-years away, with a mass of 0.386 solar masses, a radius of 0.378 solar radii, and a temperature of 3510 K. Its reported mass and radius are smaller than the Sun's, and its reported temperature is cooler. Three planets are known to orbit this host. All three were found by the transit method in 2019, in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness.

TOI-270 b is an Earth-like planet with a radius of 1.28 Earth radii, a mass of 1.48 Earth masses, and an orbital period of 3.36 days. Among the listed planets, it has the shortest year, the smallest radius, and the smallest reported mass. Its mean density is 3.89 g/cm³, 0.706 times Earth's. TOI-270 c is a Super-Earth with a radius of 2.33 Earth radii, a mass of 6.2 Earth masses, and an orbital period of 5.66 days. Among the listed planets, it has the second-shortest year, the largest radius, and the largest reported mass. Its mean density is 2.7 g/cm³, 0.49 times Earth's.

TOI-270 d is a Super-Earth with a radius of 2 Earth radii, a mass of 4.2 Earth masses, and an orbital period of 11.4 days. Among the listed planets, it has the longest year, the second-smallest radius, and the second-smallest reported mass. Its mean density is 2.89 g/cm³, 0.525 times Earth's. Each planet's reported radius and mass are larger than Earth's.