| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h04m 34.65147s[1] |
| Declination | +5° 30′ 10.3032″[1] |
| Apparent magnitude (V) | 5.593[2] |
| Characteristics | |
| Spectral type | K5 III[3] |
| U−B color index | +1.934[2] |
| B−V color index | +1.651[2] |
| Astrometry | |
| Radial velocity (Rv) | –15.26 ± 0.2[4] km/s |
| Proper motion (μ) | RA: +13.15[1] mas/yr Dec.: +0.66[1] mas/yr |
| Parallax (π) | 4.24 ± 0.42 mas[1] |
| Distance | 770 ± 80 ly (240 ± 20 pc) |
| Absolute magnitude (MV) | –1.02[5] |
| Details | |
| Radius | 63[6] R☉ |
| Luminosity | 949[7] L☉ |
| Temperature | 3,893[8] K |
| Rotational velocity (v sin i) | 4.6[7] km/s |
| Other designations | |
ζ Equ, 3 Equ, BD+04° 4606, HD 200644, HIP 104031, HR 8066, SAO 126518.[9] | |
| Database references | |
| SIMBAD | data |
3 Equulei is a single[3] star located in the small northern constellationofEquuleus. It is faintly visible to the naked eye at an apparent visual magnitude of 5.6.[2] Based upon an annual parallax shift of 4.24 mas,[1] 3 Equulei is roughly 770 light-years (240 parsecs) distant from Earth, give or take an 80 light-year margin of error. At that distance, the apparent brightness of the star is diminished by 0.15 in visual magnitude because of extinction from interstellar gas and dust.[4]
3 Equulei has been referred to in some sources as ζ (Zeta) Equulei, although it was not given that designation by Bayer.[10]
3 Equulei is an evolved giant star with a stellar classification of K5 III.[3] The measured angular diameter of this star, after correction for limb darkening, is 2.44 ± 0.03 mas.[11] At the estimated distance of 770 light-years,[1] this yields a physical size of about 63 times the radius of the Sun.[6] It is radiating an estimated 949[7] times the luminosity of the Sun from this expanded outer envelope at an effective temperature of 3,893 K.[8] At this heat, it shines with the orange-hued glow of a K-type star.[12]
