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Gliese 806

Gliese 806
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 45m 04.09925s[1]
Declination +44° 29′ 56.6451″[1]
Apparent magnitude (V) +10.79[2]
Characteristics
Spectral type dM1.5[3]
B−V color index 1.491±0.005[2]
Astrometry
Radial velocity (Rv)−24.99±0.15[1] km/s
Proper motion (μ) RA: 434.028 mas/yr[1]
Dec.: 271.022 mas/yr[1]
Parallax (π)82.8903 ± 0.0167 mas[1]
Distance39.348 ± 0.008 ly
(12.064 ± 0.002 pc)
Details
Mass0.423±0.010[3] M☉
Radius0.4144±0.0038[4] R☉
Luminosity0.0026±0.0003[3] L☉
Surface gravity (log g)4.89±0.07[3] cgs
Temperature3,586±51[3] K
Metallicity [Fe/H]−0.28±0.07[4] dex
Rotation34.6–48.1 d[4]
Rotational velocity (v sin i)0.46[5] km/s
Age~3[6] Gyr
Other designations
NSV 13280, BD+44 3567, GJ 806, HIP 102401, LTT 16068, TOI-4481, TIC 239332587, TYC 3178-00633-1, 2MASS J20450403+4429562[7][8]
Database references
SIMBADdata

Gliese 806 is a star in the northern constellation of Cygnus, located about a degree to the southeast of the bright star Deneb.[9] It is invisible to the naked eye with an apparent visual magnitude of +10.79.[2] The star is located at a distance of 39.3 light years from the Sun based on stellar parallax.[1] It is drifting closer with a radial velocity of −24.6 km/s, and is predicted to come to within 30.1 light-years in ~198,600 years.[10] The star hosts two known planetary companions.[4]

The stellar classification of Gliese 806 is dM1.5,[3] which indicates this is a small red dwarf star – an M-type main-sequence star that is generating energy through core hydrogen fusion. It is roughly three[6] billion years old and is spinning with a projected rotational velocity of 0.46 km/s.[5] The star has 42% of the mass and radius of the Sun. It is radiating 0.3% of the luminosity of the Sun from its photosphere at an effective temperature of 3,586 K.[3]

Planetary system

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In 1989, Marcy and Benitz detected a periodicity of 416 days in radial velocity variation, inferring the possible presence of a companion with a mass of about 0.011 M☉.[11] However, this candidate object was never confirmed.

More recently, observations by TESS have found a candidate transiting planet with a period of less than a day.[8] In January 2023, this planet was confirmed and a second, non-transiting planet found via radial velocity observations. A third radial velocity signal was also found, but the study was unable to confirm it as having a planetary origin. All known planets are super-Earths, and the inner transiting planet Gliese 806 b is likely to be rocky.[4]

The Gliese 806 planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 1.90±0.17 M🜨 0.01406±0.00030 0.9263237±0.0000009 — 87.7+0.6
−0.5° 		1.331±0.023 R🜨
c ≥5.80±0.30 M🜨 0.0523±0.0011 6.64064±0.00025 — — —
(unconfirmed) ≥8.50±0.45 M🜨 0.0844±0.0017 13.60588±0.00065 — — —

See also

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References

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  1. ^ a b c d e f 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 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 e f g 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 c d e f Palle, E.; Orell-Miquel, J.; et al. (October 2023). "GJ 806 (TOI-4481): A bright nearby multi-planetary system with a transiting hot, low-density super-Earth". Astronomy & Astrophysics. 678: A80. arXiv:2301.06873. Bibcode:2023A&A...678A..80P. doi:10.1051/0004-6361/202244261.
  5. ^ a b Houdebine, E. R. (September 2010), "Observation and modelling of main-sequence star chromospheres - XIV. Rotation of dM1 stars", Monthly Notices of the Royal Astronomical Society, 407 (3): 1657–1673, Bibcode:2010MNRAS.407.1657H, doi:10.1111/j.1365-2966.2010.16827.x
  6. ^ a b Mann, Andrew W.; et al. (May 2015), "How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius", The Astrophysical Journal, 804 (1): 38, arXiv:1501.01635, Bibcode:2015ApJ...804...64M, doi:10.1088/0004-637X/804/1/64, S2CID 19269312, 64
  7. ^ "GJ 806". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-09.
  8. ^ a b "ExoFOP TIC 239332587". exofop.ipac.caltech.edu. Archived from the original on 1 January 2023. Retrieved 1 January 2023.
  9. ^ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 3. Sky Publishing Corporation and the European Space Agency. p. 1127. ISBN 0-933346-84-0.
  10. ^ Bailer-Jones, C. A. L. (January 2018). "The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release". Astronomy & Astrophysics. 609: 16. arXiv:1708.08595. Bibcode:2018A&A...609A...8B. doi:10.1051/0004-6361/201731453. S2CID 119462489. A8.
  11. ^ Marcy, Geoffrey W.; Benitz, Karsten J. (1989). "A search for substellar companions to low-mass stars". Astrophysical Journal, Part 1. 344 (1): 441–453. Bibcode:1989ApJ...344..441M. doi:10.1086/167812.