Gliese 393

Gliese 393, or GJ 393, is a single^[7] star in the equatorial constellation of Sextans, positioned about 1.5° to the NNW of Beta Sextantis.^[8] At an apparent visual magnitude of 9.65,^[2] it is much too faint to be seen with the unaided eye. This star is located at a distance of 22.9 light years from the Sun based on parallax,^[1] and is drifting further away with a radial velocity of +8.3 km/s.^[2] It has a large proper motion, traversing the celestial sphere at the rate of 0.950″ per year.^[9] The net velocity of this star relative to the Sun is 32.9 km/s.^[2] It shares a similar space motion as members of the AB Doradus moving group, but is considered a random interloper.^[5]

The stellar classification of GJ 393 is M2V,^[3] indicating this is a small red dwarf star that is generating energy through core hydrogen fusion. It is rotating slowly and appears to be chromospherically inactive, suggesting it is an older star; perhaps as much as 10 billion years old.^[5] The star has 43% of the mass of the Sun and 44.6% of the Sun's radius. The metallicity, what astronomers term the abundance of heavy elements, is lower than in the Sun. It is radiating just 2.7% of the Sun's luminosity from its photosphere at an effective temperature of 3,579 K.^[3]

Planetary system[]

In 2019 one candidate planet was detected by the radial velocity method. It is classified as a hot super-Earth, with an orbital period of one week and a semimajor axis of 8.2 Gm. Longer period signals found in the data were interpreted as stellar activity.^[10]

In 2021, the planet was confirmed as real after being detected independently in three different datasets.^[11]