Alpha Equulei
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h 15m 49.437s |
| Declination | +05° 14′ 52.41″ |
| Apparent magnitude (V) | +3.919 (4.476 + 4.496) |
| Characteristics | |
| Spectral type | G7III + kA3hA4mA9 |
| U−B color index | +0.284 |
| B−V color index | +0.529 |
| Astrometry | |
| Radial velocity (Rv) | −16.458±0.027 km/s |
| Proper motion (μ) | RA: +49.747 mas/yr Dec.: −89.846 mas/yr |
| Parallax (π) | 18.11±0.24 mas |
| Distance | 180 ± 2 ly (55.2 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.146 (0.689 + 1.159) |
| Orbit | |
| Period (P) | 98.80450±0.00035 days |
| Semi-major axis (a) | 0.66±0.02 au |
| Eccentricity (e) | 0.00417±0.00076 |
| Inclination (i) | 151.52±0.28° |
| Longitude of the node (Ω) | 216.57±0.16° |
| Periastron epoch (T) | 2,457,277.7±1.7 |
| Argument of periastron (ω) (primary) | 102.9±6.3° |
| Semi-amplitude (K1) (primary) | 16.190±0.036 km/s |
| Semi-amplitude (K2) (secondary) | 18.92±0.61 km/s |
| Details | |
| A | |
| Mass | 2.20±0.16 M☉ |
| Radius | 9.20±0.01 R☉ |
| Luminosity | 47.9+12.4 −9.8 L☉ |
| Surface gravity (log g) | 3.08±0.11 cgs |
| Temperature | 5,160±65 K |
| Metallicity [Fe/H] | +0.11±0.06 dex |
| Rotational velocity (v sin i) | 5.53±0.14 km/s |
| Age | 1.0–1.2 Gyr |
| B | |
| Mass | 1.883±0.083 M☉ |
| Radius | 2.60±0.03 R☉ |
| Luminosity | 26.9+3.3 −2.9 L☉ |
| Surface gravity (log g) | 3.87±0.15 cgs |
| Temperature | 8,260±218 K |
| Metallicity [Fe/H] | +0.14±0.16 dex |
| Rotational velocity (v sin i) | 25.88±3.45 km/s |
| Age | 1.0–1.2 Gyr |
| Other designations | |
| Kitalphar, 8 Equulei, HR 8131, HD 202447, BD+04 4635, HIP 104987, SAO 126662, FK5 800, GC 29735 | |
| Database references | |
| SIMBAD | data |
Alpha Equulei (α Equulei, abbreviated Alpha Equ, α Equ), officially named Kitalpha /kɪˈtælfə/, is the brightest star in the constellation of Equuleus. It is a binary system with an orbital period of 98.8 days and a sky separation of a few milliarcseconds, too small to be resolved with the naked eye.