Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Capricornus |
Right ascension | 21h 28m 12.20609s [1] |
Declination | −21° 43′ 34.5182″ [1] |
Apparent magnitude (V) | 7.99 [2] |
Characteristics | |
Spectral type | G5V [3] |
Apparent magnitude (B) | 8.687 [2] |
Apparent magnitude (J) | 6.812±0.024 [2] |
Apparent magnitude (H) | 6.539±0.040 [2] |
Apparent magnitude (K) | 6.459±0.018 [2] |
B−V color index | 0.697±0.022 [2] |
Astrometry | |
Radial velocity (Rv) | −9.79±0.12 [1] km/s |
Proper motion (μ) |
RA: 42.751
mas/
yr
[1] Dec.: −270.443 mas/ yr [1] |
Parallax (π) | 20.7705 ± 0.0343 mas [1] |
Distance | 157.0 ± 0.3
ly (48.15 ± 0.08 pc) |
Absolute magnitude (MV) | 4.61 [2] |
Details | |
Mass | 1.06±0.03 [4] M☉ |
Radius | 1.08±0.03 [4] R☉ |
Luminosity | 1.18±0.03 [4] L☉ |
Surface gravity (log g) | 4.39±0.04 [4] cgs |
Temperature | 5,783±48 [4] K |
Metallicity [Fe/H] | 0.18 [5] dex |
Rotational velocity (v sin i) | 0.846 [5] km/s |
Age | 4.3±1.8 [4] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 204313 is a star with two and possibly three exoplanetary companions in the southern constellation of Capricornus. With an apparent magnitude of 7.99, [2] it is an eighth magnitude star that is too faint to be readily visible to the naked eye. The star is located at a distance of 157 light years from the Sun based on parallax measurements, but it is drifting closer with a radial velocity of −10 km/s. [1]
This is an ordinary G-type main-sequence star with a stellar classification of G5V, [3] which indicates it is generating energy through hydrogen fusion at its core. It is an estimated four billion years old, chromospherically extremely quiet, [7] and is spinning with a projected rotational velocity of just 0.8 km/s. [5] The star has a slightly larger mass and radius compared to the Sun. It is radiating 118% of the luminosity of the Sun from its photosphere at an effective temperature of 5,783 K. [4]
This star was in observation by the CORALIE radial velocity planet-search program since the year 2000. In August 2009, a superjovian planetary companion was announced. [8] Two years later, a hot Neptune HD 204313 c on a 35-day orbit was announced, [9] followed by a third Jupiter-like planet candidate HD 204313 d on a 2800-day orbit, which was announced in 2012. [10] Assuming that planet d exists, planets b & d are apparently orbiting close to a 7:5 mean motion resonance, which may be stabilizing their periods. [11]
A 2015 study independently confirmed the first two discoveries, but did not detect any significant signal at the claimed period of planet d. [12] Another study in 2022 agreed with these results, in addition to finding a new planet or brown dwarf, designated HD 204313 e to differentiate it from the dubious candidate. The inclination and true mass of planets b & e were measured via astrometry. [13]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
c | ≥17.6±1.7 M🜨 | 0.2099±0.0071 | 34.905±0.012 | 0.059+0.051 −0.041 |
— | — |
b | 4.615+1.290 −0.306 MJ |
3.185+0.130 −0.143 |
2041.1+1.7 −1.9 |
0.100±0.003 | 72.917+31.372 −21.476 ° |
— |
e | 15.317+4.890 −5.183 MJ |
7.457+0.399 −0.427 |
7325.6+399.9 −369.1 |
0.253+0.071 −0.065 |
176.092+0.963 −2.122 ° |
— |