Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
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 mas [1] |
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]
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 ° | — |