HD 6718
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 01h 07m 48.6630s[1] |
| Declination | –08° 14′ 01.3306″[1] |
| Apparent magnitude (V) | 8.45[2] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | G5V[3] |
| Apparent magnitude (B) | 9.087[4] |
| Apparent magnitude (J) | 7.269[5] |
| Apparent magnitude (H) | 6.99[5] |
| Apparent magnitude (K) | 6.876[5] |
| B−V color index | 0.662±0.009[2] |
| Astrometry | |
| Radial velocity (Rv) | +34.76[2] km/s |
| Proper motion (μ) | RA: 192.637±0.114[1] mas/yr Dec.: 20.080±0.069[1] mas/yr |
| Parallax (π) | 19.4476 ± 0.0523 mas[1] |
| Distance | 167.7 ± 0.5 ly (51.4 ± 0.1 pc) |
| Absolute magnitude (MV) | 4.754[6] |
| Details | |
| Mass | 0.98±0.04[7] M☉ |
| Radius | 1.01±0.02[7] R☉ |
| Luminosity | 1.07±0.01[7] L☉ |
| Surface gravity (log g) | 4.42±0.02[8] cgs |
| Temperature | 5,728±5[8] K |
| Metallicity [Fe/H] | −0.064±0.004[8] dex |
| Rotational velocity (v sin i) | 2.00±0.12[8] km/s |
| Age | 6.0±2.4[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 6718 is a solar twin[10] star in the equatorial constellation of Cetus. It has a yellow hue but is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.45.[2] The distance to this object, as determined from parallax measurements, is 168 light years. It is drifting away from the Sun with a radial velocity of +35 km/s.[2]
This object is an ordinary G-type main-sequence star with a stellar classification of G5V,[3] with the luminosity class of 'V' indicating it is generating energy through hydrogen fusion at its core. It is around six billion years old with a leisurely rotation rate, having a projected rotational velocity of 2 km/s.[8] The level of magnetic activity in the chromosphere is considered very low[6] and it has a near solar metallicity.[8] Being a solar twin, has nearly the same mass and radius as the Sun. The star is radiating 1.07[7] times the luminosity of the Sun from its photosphere at an effective temperature of 5,728 K.[8]
In 2009, a substellar companion (HD 6718 b) with a minimum mass of 1.56 MJ was found in orbit around the star with a period of 6.83 years.[6] In 2020, the inclination of this object was measured, revealing its true mass to be 62.8 MJ. This makes it a brown dwarf.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 62.79+16.98 −13.80 MJ |
3.56+0.24 −0.15 |
2496±176 | 0.10+0.11 −0.04 |
1.488+0.410 −0.310° |
— |
See also
[edit]References
[edit]- ^ a b c d e 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.
- ^ a b c d e 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 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
- ^ Høg, E.; et al. (2000). The Tycho-2 catalogue of the 2.5 million brightest stars. Vol. 355. pp. L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 978-0333750889.
((cite book)):|journal=ignored (help) - ^ a b c Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; et al. (June 2003). "2MASS All Sky Catalog of point sources". The IRSA 2MASS All-Sky Point Source Catalog, NASA/IPAC Infrared Science Archive. Bibcode:2003tmc..book.....C.
- ^ a b c d Naef, Dominique; Mayor, Michel; Lo Curto, Gaspare; Bouchy, François; Lovis, Christophe; Moutou, Claire; Benz, Willy; Pepe, Francesco; Queloz, Didier; Santos, Nuno C.; Ségransan, Damien; Udry, Stéphane; Bonfils, Xavier; Delfosse, Xavier; Forveille, Thierry; Hébrard, Guillaume; Mordasini, Christoph; Perrier, Christian; Boisse, Isabelle; Sosnowska, Danuta (2010). "The HARPS Search for Southern Extrasolar Planets XXIII. 8 Planetary Companions to Low-activity Solar-type Stars". Astronomy and Astrophysics. 523: A15. arXiv:1008.4600. Bibcode:2010A&A...523A..15N. doi:10.1051/0004-6361/200913616. S2CID 118845989.
- ^ a b c d e Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID 54555839.
- ^ a b c d e f g dos Santos, Leonardo A.; et al. (August 2016), "The Solar Twin Planet Search. IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars", Astronomy & Astrophysics, 592: 8, arXiv:1606.06214, Bibcode:2016A&A...592A.156D, doi:10.1051/0004-6361/201628558, S2CID 53533614, A156.
- ^ "HD 6718". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2014-09-08.
- ^ Ramírez, I.; et al. (December 2014). "The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample". Astronomy & Astrophysics. 572: 19. arXiv:1408.4130. Bibcode:2014A&A...572A..48R. doi:10.1051/0004-6361/201424244. S2CID 46964342. A48.
- ^ a b Kiefer, F.; et al. (January 2021). "Determining the true mass of radial-velocity exoplanets with Gaia. Nine planet candidates in the brown dwarf or stellar regime and 27 confirmed planets". Astronomy & Astrophysics. 645 A7. arXiv:2009.14164. Bibcode:2021A&A...645A...7K. doi:10.1051/0004-6361/202039168. S2CID 221995447.
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