HD 200779
High proper motion star; Equuleus
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HD 200779 (HIP 104092; Gliese 818; LHS 3624) is a solitary star located in the equatorial constellation Equuleus, the foal. It has an apparent magnitude of 8.27,[3] making it readily visible in binoculars but not to the naked eye. The object is located relatively close at a distance of 49 light years based on Gaia DR3 parallax measurements,[2] which makes it the nearest star in Equuleus.[13] It is classified as a high proper motion star,[12] with a total proper motion of 569 mas/yr.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Equuleus[1] |
| Right ascension | 21h 05m 19.74605s[2] |
| Declination | +07° 04′ 09.4729″[2] |
| Apparent magnitude (V) | 8.27[3] |
| Characteristics | |
| Spectral type | K6 V[4] |
| U−B color index | +1.12[5] |
| B−V color index | +1.21[5] |
| R−I color index | +0.61[3] |
| Astrometry | |
| Radial velocity (Rv) | −66.94±0.18[6] km/s |
| Proper motion (μ) | RA: +78.562 mas/yr[2] Dec.: −563.909 mas/yr[2] |
| Parallax (π) | 66.4626±0.0225 mas[2] |
| Distance | 49.07 ± 0.02 ly (15.046 ± 0.005 pc) |
| Absolute magnitude (MV) | +7.38[1] |
| Details | |
| Mass | 0.68±0.01[7] M☉ |
| Radius | 0.689+0.077 −0.050[8] R☉ |
| Luminosity | 0.18[9] L☉ |
| Surface gravity (log g) | 4.67±0.02[7] cgs |
| Temperature | 4,406±73[10] K |
| Metallicity [Fe/H] | +0.05±0.06[7] dex |
| Rotational velocity (v sin i) | 5.1±1.2[6] km/s |
| Age | 6.33[11] Gyr |
| Other designations | |
| AG+06°2882, BD+06°4741, GC 29447, GJ 818, HD 200779, HIP 104092, SAO 126533, CCDM J21054+0704A, WDS J21053+0704A, LFT 160, LHS 3624, LTT 16169[12] | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
At its current distance, HD 200779's brightness is diminished by only six hundredths of a magnitude due to interstellar dust[14] and it has an absolute magnitude of +7.38.[1] HD 200779 is expected to come within 7.76 parsecs (25.3 ly) of the Solar System in roughly 160,000 years.[15]
HD 200779 is an ordinary K-type main-sequence star with a stellar classification of K6 V.[4] It has 68% the mass of the Sun[7] and 69% of its radius.[8] However, it only radiates 18% the luminosity of the Sun[9] from its photosphere at an effective temperature of 4,406 K,[10] giving it an orange hue. It has an iron abundance slightly above solar level at [Fe/H] = +0.05[7] and it is estimated to be 6.33 billion years old.[11] HD 200779 spins modestly with a projected rotational velocity of 5.1 km/s.[6] The star is generally considered to be chromospherically active.[4]
HD 200779 has two optical companions: a distant 11th magnitude star located 64.6" away and a 9th magnitude star located 169.4" away.[16]