HD 21819
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Camelopardalis[1] |
| Right ascension | 03h 33m 39.06000s[2] |
| Declination | +54° 58′ 29.4970″[2] |
| Apparent magnitude (V) | 5.97±0.01[3] |
| Characteristics | |
| Evolutionary stage | main sequence star[4] |
| Spectral type | A3 V[5] or A2 Vp[6] |
| B−V color index | +0.11[7] |
| Astrometry | |
| Radial velocity (Rv) | −6.5±1.5[8] km/s |
| Proper motion (μ) | RA: −41.053 mas/yr[2] Dec.: −0.357 mas/yr[2] |
| Parallax (π) | 13.1723±0.0317 mas[2] |
| Distance | 247.6 ± 0.6 ly (75.9 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.62[1] |
| Details | |
| Mass | 2.00+0.19 −0.15[9] M☉ |
| Radius | 2.06±0.10[10] R☉ |
| Luminosity | 30.6+2.2 −2.0[4] L☉ |
| Surface gravity (log g) | 4.08[11] cgs |
| Temperature | 9,000[12] K |
| Metallicity [Fe/H] | −0.17[11] dex |
| Rotational velocity (v sin i) | 160±8[6] km/s |
| Age | 737±102[9] Myr |
| Other designations | |
| AG+54°370, BD+54°693, GC 4229, HD 21819, HIP 16599, HR 1073, SAO 24099, TIC 316848255[13] | |
| Database references | |
| SIMBAD | data |
HD 21819, also designated as HR 1073, is a solitary star[14] located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.97,[3] making faintly visible to the naked eye under ideal conditions. The object is located relatively close at a distance of 248 light-years based on Gaia DR3 parallax measurements[2] and it is drifting closer with a heliocentric radial velocity of −6.5 km/s.[8] At its current distance, HD 21819's brightness is diminished by an interstellar extinction of 0.17 magnitudes[15] and it has an absolute magnitude of +1.62.[1]
HD 21819 has a stellar classification of A3 V,[5] indicating that it is an ordinary A-type main-sequence star that is generating energy via hydrogen fusion at its core. Abt & Morell (1995) gave a slightly hotter star of A2 Vp,[6] indicating that it is instead an Ap star with weak magnesium lines. It has twice the mass of the Sun[9] and 2.06 times the radius of the Sun.[10] It radiates 30.6 times the luminosity of the Sun[4] from its photosphere at an effective temperature of 9,000 K,[12] giving it a white hue when viewed in the night sky. HD 21819 is metal deficient with an iron abundance of [Fe/H] = −0.17 or 67.6% of the Sun's[11] and it is estimated to be 737 million years old,[9] having completed 55.7% of its main sequence lifetime.[4] Like most hot stars it spins rapidly, having a projected rotational velocity of 160 km/s.[6]
