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]
| 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] |
| Distance | 39.348 ± 0.008 ly (12.064 ± 0.002 pc) |
| Details | |
| Mass | 0.423±0.010[3] M☉ |
| Radius | 0.4144±0.0038[4] R☉ |
| Luminosity | 0.0026±0.0003[3] L☉ |
| Surface gravity (log g) | 4.89±0.07[3] cgs |
| Temperature | 3,586±51[3] K |
| Metallicity [Fe/H] | −0.28±0.07[4] dex |
| Rotation | 34.6–48.1 d[4] |
| Rotational velocity (v sin i) | 0.46[5] km/s |
| Age | ~3[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
editIn 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]
| 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
editReferences
edit- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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
- ^ 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
- ^ "GJ 806". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-09.
- ^ a b "ExoFOP TIC 239332587". exofop.ipac.caltech.edu. Archived from the original on 1 January 2023. Retrieved 1 January 2023.
- ^ 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.
- ^ 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.
- ^ 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.