Gliese 393, or GJ 393, is a single[7] star with an orbiting exoplanet companion 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]

Gliese 393
Observation data
Epoch J2000      Equinox J2000
Constellation Sextans
Right ascension 10h 28m 55.551s[1]
Declination +00° 50′ 27.60″[1]
Apparent magnitude (V) 9.65[2]
Characteristics
Spectral type M2V[3]
U−B color index 1.192[2]
B−V color index 1.507±0.014[2]
Astrometry
Radial velocity (Rv)+8.34±0.10[2] km/s
Proper motion (μ) RA: −602.992 mas/yr[1]
Dec.: −731.882 mas/yr[1]
Parallax (π)142.0951 ± 0.0212 mas[1]
Distance22.953 ± 0.003 ly
(7.038 ± 0.001 pc)
Absolute magnitude (MV)10.40[2]
Details[3]
Mass0.432±0.011 M
Radius0.4459±0.0073 R
Luminosity0.02687±0.00054 L
Surface gravity (log g)4.88±0.07 cgs
Temperature3,579±51 K
Metallicity [Fe/H]−0.09±0.16 dex
Rotation34.15±0.22 d[4]
Rotational velocity (v sin i)1.5[5] km/s
Age3.28[4] Gyr
Other designations
BD+01°2447, GJ 393, HIP 51317, LTT 12805, 2MASS J10285555+0050275[6]
Database references
SIMBADdata

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

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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]

The Gliese 393 planetary system[11]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b ≥1.71±0.24 M🜨 0.05402±0.00072 7.02679+0.00082
−0.00085
0
 
Artist's impression and size comparison of the planet Gliese 393 b with Earth, assuming Earth-like composition

References

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  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d e f g h Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644
  3. ^ a b c d Schweitzer, A.; et al. (May 2019). "The CARMENES search for exoplanets around M dwarfs. Different roads to radii and masses of the target stars". Astronomy & Astrophysics. 625: 16. arXiv:1904.03231. Bibcode:2019A&A...625A..68S. doi:10.1051/0004-6361/201834965. S2CID 102351979. A68.
  4. ^ a b Engle, Scott G.; Guinan, Edward F. (September 2023). "Living with a Red Dwarf: The Rotation-Age Relationships of M Dwarfs". The Astrophysical Journal Letters. 954 (2): L50. arXiv:2307.01136. Bibcode:2023ApJ...954L..50E. doi:10.3847/2041-8213/acf472. L50.
  5. ^ a b c Schaefer, G. H.; et al. (May 2018), "AB Dor Moving Group Stars Resolved with the CHARA Array", The Astrophysical Journal, 858 (2): 14, Bibcode:2018ApJ...858...71S, doi:10.3847/1538-4357/aaba71, S2CID 48362791, 71
  6. ^ "GJ 393". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-08.
  7. ^ Winters, Jennifer G.; et al. (June 2019). "The Solar Neighborhood. XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc". The Astronomical Journal. 157 (6): 32. arXiv:1901.06364. Bibcode:2019AJ....157..216W. doi:10.3847/1538-3881/ab05dc. S2CID 86859146. 216.
  8. ^ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 2. Sky Publishing Corporation and the European Space Agency. p. 779. ISBN 0-933346-83-2.
  9. ^ Lépine, Sébastien; Shara, Michael M. (March 2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. S2CID 2603568.
  10. ^ Barnes, J. R.; et al. (2019-06-11). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644 [astro-ph.EP].
  11. ^ a b Amado, Pedro J.; et al. (2021-05-28). "The CARMENES search for exoplanets around M dwarfs". Astronomy & Astrophysics. 650: A188. arXiv:2105.13785. Bibcode:2021A&A...650A.188A. doi:10.1051/0004-6361/202140633. S2CID 235248027.