Epsilon Andromedae, Latinized from ε Andromedae, is a star in the constellationofAndromeda.[4] It can be seen with the naked eye, having an apparent visual magnitude of 4.4.[2] Based upon an annual parallax shift of 21.04 mas as seen from Earth,[1] it is located 155 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −84 km/s.[6] Its orbit in the Milky Way is highly eccentric, causing it to move rapidly relative to the Sun and its neighboring stars.[8]
| |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h38m 33.34610s[1] |
| Declination | +29° 18′ 42.3135″[1] |
| Apparent magnitude (V) | 4.357[2] |
| Characteristics | |
| Spectral type | G6 III Fe−3 CH1[3] |
| U−B color index | +0.463[2] |
| B−V color index | +0.8713[2] |
| V−R color index | +0.6[4] |
| R−I color index | +0.51[5] |
| Astrometry | |
| Radial velocity (Rv) | −84.43±0.15[6] km/s |
| Proper motion (μ) | RA: −229.04[1] mas/yr Dec.: −253.11[1] mas/yr |
| Parallax (π) | 19.91 ± 0.19 mas[1] |
| Distance | 164 ± 2 ly (50.2 ± 0.5 pc) |
| Absolute magnitude (MV) | +0.69[7] |
| Details[6] | |
| Mass | 1.01±0.35 M☉ |
| Radius | 9.04±0.34 R☉ |
| Luminosity | 51.3 L☉ |
| Surface gravity (log g) | 2.88±0.02 cgs |
| Temperature | 5,082±20 K |
| Metallicity [Fe/H] | −0.53±0.05 dex |
| Rotational velocity (v sin i) | 1.70±0.45 km/s |
| Age | 5.71±5.29 Gyr |
| Other designations | |
ε And, 30 Andromedae, BD+28° 103, FK5 19, GC 759, HD 3546, HIP 3031, HR 163, SAO 74164, PPM 90002, LTT 10215, NLTT 2065[4] | |
| Database references | |
| SIMBAD | data |
This is an evolved G-type giant star with a stellar classificationofG6 III Fe−3 CH1.[3] The suffix notation indicates there is a strong underabundance of iron in the spectrum, and an overabundance of cyanogen (CN). ε Andromedae is believed to be a red clump[9] star which is fusing helium in its core. It has about the same mass as the Sun, but has expanded to nine times the Sun's radius. The star is radiating 51 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,082 K.[6]
InChinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of ε Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, the Chinese name for ε Andromedae itself is 奎宿四 (Kuí Sù sì, English: the Fourth Star of Legs.)[10]
