HD 169904
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 18h 42m 14.42015s[1] |
| Declination | −81° 48′ 29.2064″[1] |
| Apparent magnitude (V) | 6.26±0.01[2] |
| Characteristics | |
| Evolutionary stage | main sequence star[3] |
| Spectral type | B8 V[4] |
| U−B color index | −0.37[5] |
| B−V color index | −0.13[5] |
| Variable type | suspected[6] |
| Astrometry | |
| Radial velocity (Rv) | −6.0±4.3[7] km/s |
| Proper motion (μ) | RA: +13.838 mas/yr[1] Dec.: −16.605 mas/yr[1] |
| Parallax (π) | 6.7598±0.0413 mas[1] |
| Distance | 482 ± 3 ly (147.9 ± 0.9 pc) |
| Absolute magnitude (MV) | +0.19[8] |
| Details | |
| Mass | 3.25±0.06[3] M☉ |
| Radius | 2.42±0.12[9] R☉ |
| Luminosity | 141+14 −13[3] L☉ |
| Surface gravity (log g) | 4.20[10] cgs |
| Temperature | 13,622[11] K |
| Metallicity [Fe/H] | −0.18[12] dex |
| Rotational velocity (v sin i) | 123[13] km/s |
| Other designations | |
| 35 G. Octantis[14], NSV 24510, CD−81°693, CPD−81°813, GC 25366, HD 169904, HIP 91723, HR 6912, SAO 258804, TIC 351920521[15] | |
| Database references | |
| SIMBAD | data |
HD 169904 (HR 6912; 35 G. Octantis) is a solitary star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.26,[2] placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 482 light-years[1] and it is currently drifting closer with a somewhat constrained radial velocity of −6.0 km/s.[7] At its current distance, HD 169904's brightness is diminished by 0.24 magnitudes due to interstellar extinction[16] and it has an absolute magnitude of +0.19.[8]
HD 169904 has a stellar classification of B8 V,[4] indicating that it is an ordinary B-type main-sequence star that is generating energy via hydrogen fusion at its core. It has 3.25 times the mass of the Sun[3] and 2.42 times the radius of the Sun.[9] It radiates 141 times the luminosity of the Sun[3] from its photosphere at an effective temperature of 13,622 K,[11] giving it a blue-white hue when viewed in the night sky. HD 169904 is metal deficient with an iron abundance of [Fe/H] = −0.18 or 66.1% of the Sun's,[12] and it spins rapidly with a projected rotational velocity of 123 km/s.[13] HD 169904 is estimated to have completed 47.5% of its main sequence lifetime.[3]
The object was listed as a suspected variable star based on photometric observations,[6] but subsequent observations have not confirmed this.[17]
