Astronomy:HD 202206
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 21h 14m 57.76850s[1] |
| Declination | −20° 47′ 21.1624″[1] |
| Apparent magnitude (V) | +8.07±0.01[2] |
| Characteristics | |
| Spectral type | G6V[3] + M8V[2] |
| B−V color index | 0.714±0.012[4] |
| Astrometry | |
| Radial velocity (Rv) | +14.68±0.23[5] km/s |
| Proper motion (μ) | RA: −39.079[1] mas/yr Dec.: −119.999[1] mas/yr |
| Parallax (π) | 21.7264 ± 0.0651[1] mas |
| Distance | 150.1 ± 0.4 ly (46.0 ± 0.1 pc) |
| Absolute magnitude (MV) | +4.80[4] |
| Orbit[2] | |
| Period (P) | 256.33 days |
| Semi-major axis (a) | 1.40±0.10 mas |
| Eccentricity (e) | 0.432±0.001 |
| Inclination (i) | 10.9±0.8° |
| Longitude of the node (Ω) | 121±4° |
| Periastron epoch (T) | 2,452,176.14±0.12 JD |
| Argument of periastron (ω) (secondary) | 161.9±0.2° |
| Semi-amplitude (K1) (primary) | 0.567±0.001 km/s |
| Details | |
| A | |
| Mass | 1.07±0.08[2] M☉ |
| Radius | 1.05+0.02 −0.03[1] R☉ |
| Luminosity | 1.084+0.004 −0.005[1] L☉ |
| Surface gravity (log g) | 4.5±0.1[2] cgs |
| Temperature | 5,735+76 −74[1] K |
| Metallicity [Fe/H] | 0.29±0.01[4] dex |
| Rotational velocity (v sin i) | 2.3±0.5[2] km/s |
| Age | 2.9±1.0[2] Gyr |
| B | |
| Mass | 0.089+0.007 −0.006[2] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 202206 is a binary star system in the southern constellation of Capricornus. With an apparent visual magnitude of +8.1,[2] it is too faint to be visible to the naked eye. It is located at a distance of 150 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +14.7 km/s.[5]
The primary component is a G-type main-sequence star with a stellar classification of G6V,[3] indicating it is generating energy through core hydrogen fusion. It is an estimated three[2] billion years old and is spinning with a projected rotational velocity of 2.3 km/s.[2] It is a metal-rich star – what astronomers term the abundance of elements of higher atomic number than helium – which may explain the star's unusually high luminosity for its class.[7] The star has a slightly greater mass and radius compared to the Sun.[2]
Companions
In 2000, analysis of radial velocity measurements of the star revealed the existence of a brown dwarf companion[8] with at least 17 times the mass of Jupiter around the star in an eccentric orbit with a period of around 256 days.[7] Even after the brown dwarf was accounted for, the star still showed a drift in the radial velocity measurements, suggesting another companion in a longer-period orbit. In 2004 after further observations, the parameters of a proposed companion was announced.[9]
Further observation of this system revised this picture in 2017, showing that the system instead consisted of a pair of co-orbiting stars being viewed nearly face-on, with the pair being orbited in turn by a Super-Jupiter designated HD 202206 c. The secondary stellar companion, now designated component B rather than 'b', is a red dwarf star with 8.9% of the mass of the Sun.[2]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 17.9+2.9 −1.8 MJ |
2.41 | 1,260±11 | 0.22±0.03 | 7.7±1.1° | — |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 Benedict, G. Fritz; Harrison, Thomas E. (June 2017). "HD 202206: A Circumbinary Brown Dwarf System". The Astronomical Journal 153 (6): 12. doi:10.3847/1538-3881/aa6d59. 258. Bibcode: 2017AJ....153..258B.
- ↑ 3.0 3.1 Houk, N.; Smith-Moore, M. (1988). Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. 4. Bibcode: 1988mcts.book.....H.
- ↑ 4.0 4.1 4.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 5.0 5.1 Valenti, Jeff A.; Fischer, Debra A. (2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series 159 (1): 141–166. doi:10.1086/430500. Bibcode: 2005ApJS..159..141V.
- ↑ "HD 202206". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+202206.
- ↑ 7.0 7.1 Udry, S. et al. (2002). "The CORALIE survey for southern extra-solar planets VIII. The very low-mass companions of HD 141937, HD 162020, HD 168443, HD 202206: Brown dwarfs or "superplanets"?". Astronomy and Astrophysics 390 (1): 267–279. doi:10.1051/0004-6361:20020685. Bibcode: 2002A&A...390..267U.
- ↑ "Exoplanets Galore!" (Press release). Garching, Germany: European Southern Observatory. April 15, 2000. Retrieved December 30, 2012.
- ↑ Correia, A. et al. (2005). "The CORALIE survey for southern extra-solar planets. XIII. A pair of planets around HD202206 or a circumbinary planet?". Astronomy and Astrophysics 440 (2): 751–758. doi:10.1051/0004-6361:20042376. Bibcode: 2005A&A...440..751C.
External links
- HD 202206 on Extrasolar Planets Encyclopaedia
- Extrasolar Planet Interactions by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona
Coordinates: 
21h 14m 57.79s, −20° 47′ 20.1″
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