HD 13931

HD 13931 is a Sun-like star in the northern constellation of Andromeda. It can be viewed with binoculars or a small telescope but is too faint to be seen with the naked eye, having an apparent visual magnitude of 7.60.^[3] This object is located at a distance of 154 light years from the Sun, as determined from its parallax, and is drifting further away with a radial velocity of +31 km/s.^[2]

This is an ordinary G-type main-sequence star with a stellar classification of G0V,^[4] which indicates it, like the Sun, is generating energy through core hydrogen fusion. It is slightly larger, hotter, brighter, and more massive than the Sun. The metal content is about 8% greater than the Sun, and it has a quiet (magnetically inactive) chromosphere.^[7] The star is an estimated 6.8 billion years old and it is spinning with a rotation period of about 26 days^[7]

In 2009, a very long-period giant planet, more massive than Jupiter, was found in orbit around the star by measuring changes in the star's radial velocity.^[7] This planet takes 12.16 years to orbit the star^[10] at the typical distance of 5.32 AU (796 Gm). The planet's eccentricity (0.02) is about the same as Earth's.^[11] In 2023, the inclination and true mass of HD 13931 b were measured via astrometry.^[10]

According to a 2018 research, HD 13931 is the most promising Solar System analogue known, since it has a star similar to the Sun and a planet with mass and semimajor axis similar to Jupiter. Those characteristics yield a probability almost 75% for the existence of a dynamically stable habitable zone, where an Earth-like planet may exist and sustain life.^[12]