Gliese 393

Gliese 393, or GJ 393, is a single[6] star in the equatorial constellation of Sextans, positioned about 1.5° to the NNW of Beta Sextantis.[7] 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.[8] 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.[4]

Gliese 393
Observation data
Epoch J2000      Equinox J2000
Constellation Sextans
Right ascension 10h 28m 55.55130s[1]
Declination +00° 50′ 27.6018″[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: −603.003[1] mas/yr
Dec.: −732.075[1] mas/yr
Parallax (π)142.1885 ± 0.0499[1] mas
Distance22.938 ± 0.008 ly
(7.033 ± 0.002 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
Rotational velocity (v sin i)1.5[4] km/s
Other designations
BD+01°2447, GJ 393, HIP 51317, LTT 12805[5]
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.[4] 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 been 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.[9]

The Gliese 393 planetary system[9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (unconfirmed) 1.9+1.1
−1.0 M⊕		 0.055+0.005
−0.006		 7.0269+0.0034
−0.0041		 0.03+0.21
−0.03		 — —

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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. 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. A68.
  4. 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, 71
  5. "GJ 393". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-08.
  6. 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. 216.
  7. Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. 2. Sky Publishing Corporation and the European Space Agency. p. 779. ISBN 0-933346-83-2.
  8. 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.
  9. Barnes, J. R.; et al. (2019-06-11). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644. Bibcode:2019arXiv190604644T. Cite journal requires |journal= (help)
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