HD 204904
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 21h 38m 56.38010s[1] |
| Declination | −79° 26′ 33.2989″[1] |
| Apparent magnitude (V) | 6.17±0.01[2] |
| Characteristics | |
| Spectral type | F6 IV[3] or F4 IV[4] |
| U−B color index | +0.02[5] |
| B−V color index | +0.46[5] |
| Astrometry | |
| Radial velocity (Rv) | −5.2±0.5[6] km/s |
| Proper motion (μ) | RA: +71.185 mas/yr[1] Dec.: −26.928 mas/yr[1] |
| Parallax (π) | 15.369±0.0195 mas[1] |
| Distance | 212.2 ± 0.3 ly (65.07 ± 0.08 pc) |
| Absolute magnitude (MV) | +2.13[7] |
| Details | |
| Mass | 1.53[8] M☉ |
| Radius | 2.87±0.15[9] R☉ |
| Luminosity | 12.1±0.1[1] L☉ |
| Surface gravity (log g) | 3.67+0.10 −0.09[10] cgs |
| Temperature | 6,443±80[11] K |
| Metallicity [Fe/H] | −0.20±0.06[12] dex |
| Rotational velocity (v sin i) | 12±1.6[13] km/s |
| Age | 2.56[8] Gyr |
| Other designations | |
| 59 G. Octantis[14], CD−79°856, CPD−79°1158, FK5 3723, GC 30221, HD 204904, HIP 106881, HR 8234, SAO 257942, TIC 354944747[15] | |
| Database references | |
| SIMBAD | data |
HD 204904 (HR 8234; 59 G. Octantis) is a spectroscopic binary located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.17,[2] placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at distance of 212 light-years based on Gaia DR3 parallax measurements[1] and it is drifting closer with a heliocentric radial velocity of −5.2 km/s.[6] At its current distance, HD 204904's brightness is diminished by 0.19 magnitudes due to interstellar extinction[16] and it has an absolute magnitude of +2.13.[7]
HD 204904 has a stellar classification of either F6 IV or F4 IV,[4] indicating that it is a slightly evolved F-type subgiant. It has 1.53 times the mass of the Sun[8] and a slightly enlarged radius 2.87 times that of the Sun's.[9] It radiates 12.1 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 6,443 K,[11] giving it the typical yellowish-white hue of an F-type star. HD 204904 is metal deficient with an iron abundance of [Fe/H] = −0.20 or 63.1% of the Sun's iron abundance.[12] It is estimated to be 2.56 billion years old[8] and it spins modestly with a projected rotational velocity of 12 km/s.[13]
In 2014, J. R. De Medeiros and colleagues detected radial velocity variations from the star, indicating that it was a spectroscopic binary.[13] However, the system does not have a defined orbit.[17]
