HD 218108
From Wikipedia, the free encyclopedia
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 23h 08m 23.84044s[1] |
| Declination | −79° 28′ 50.4748″[1] |
| Apparent magnitude (V) | 6.11±0.01[2] |
| Characteristics | |
| Spectral type | A6 Vn[3] |
| U−B color index | +0.10[4] |
| B−V color index | +0.14[4] |
| Astrometry | |
| Radial velocity (Rv) | −7±4.4[5] km/s |
| Proper motion (μ) | RA: +93.016 mas/yr[1] Dec.: −35.907 mas/yr[1] |
| Parallax (π) | 13.1893±0.0236 mas[1] |
| Distance | 247.3 ± 0.4 ly (75.8 ± 0.1 pc) |
| Absolute magnitude (MV) | +1.78[6] |
| Details | |
| Mass | 1.80[7] M☉ |
| Radius | 2±0.1[8] R☉ |
| Luminosity | 15.24[9] L☉ |
| Surface gravity (log g) | 4.17±0.07[10] cgs |
| Temperature | 8,213±244[11] K |
| Metallicity [Fe/H] | −0.01[12] dex |
| Rotational velocity (v sin i) | 194±2[13] km/s |
| Age | 249[7] Myr |
| Other designations | |
| 79 G. Octantis[14], CPD−80°1064, FK5 3847, GC 32194, HD 218108, HIP 114258, HR 8786, SAO 258105[15] | |
| Database references | |
| SIMBAD | data |
HD 218108, also known as HR 8786, is a solitary, white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.11,[2] making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from Gaia DR3, the object is estimated to be 247 light years away.[1] It appears to be approaching the Solar System with a fairly constrained radial velocity of −7 km/s.[5] Paunzen et al. (2001) lists it as a λ Boötis star with a weak magnesium line.[16]
HD 218108 has a stellar classification of A6 Vn,[3] indicating that it is an A-type main-sequence star with broad or nebulous absorption lines due to rapid rotation. In 1966, David Stanley Evans gave it a slightly cooler class of A7 Vn.[17] However, Houk and Cowley (1975) give it a classification of A3/4 V, a main sequence star with the characteristics of an A3 and A4 star.[18] Paunzen et al. (2001) gives it a class of A3 V, indicating that it is instead an ordinary A-type main-sequence star.[16]
Nevertheless, it has 1.8 times the mass of the Sun[7] and twice its radius.[8] It radiates 15.24 times the luminosity of the Sun[9] from its photosphere at an effective temperature of 8,213 K. It is estimated to be 249 million years old[7] and is currently spinning with a high projected rotational velocity of 149 km/s.[13] A solar metallicity was calculated for HD 218108.[12]
