Alpha Coronae Borealis
Alpha Coronae Borealis (α Coronae Borealis, abbreviated Alpha CrB, α CrB), officially named Alphecca /ælˈfɛkə/, is an eclipsing binary star in the constellation of Corona Borealis. It is located about 75 light years from the Sun and contains two main sequence stars, one class A and one class G.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 15h 34m 41.268s |
| Declination | +26° 42′ 52.89″ |
| Apparent magnitude (V) | 2.24 |
| Characteristics | |
| Spectral type | A0V + G5V |
| U−B color index | −0.03 |
| B−V color index | −0.02 |
| Variable type | Eclipsing binary |
| Astrometry | |
| Radial velocity (Rv) | +1.7 km/s |
| Proper motion (μ) | RA: 120.27 mas/yr Dec.: −89.58 mas/yr |
| Parallax (π) | 43.46 ± 0.28 mas |
| Distance | 75.0 ± 0.5 ly (23.0 ± 0.1 pc) |
| Absolute magnitude (MV) | +0.16/+5.05 |
| Orbit | |
| Period (P) | 17.3599 d |
| Semi-major axis (a) | 0.2 AU (2.981 × 1012 cm) |
| Eccentricity (e) | 0.370 |
| Inclination (i) | 88.2 ± 0.1° |
| Argument of periastron (ω) (primary) | 311° |
| Details | |
| α CrB A | |
| Mass | 2.58 M☉ |
| Radius | 2.89–3.04 R☉ |
| Luminosity | 74 L☉ |
| Surface gravity (log g) | 3.89 cgs |
| Temperature | 9,700 K |
| Rotational velocity (v sin i) | 139 km/s |
| Age | 0.314 Gyr |
| α CrB B | |
| Mass | 0.92 M☉ |
| Radius | 0.90 R☉ |
| Luminosity | 0.81 L☉ |
| Surface gravity (log g) | 4.50 cgs |
| Temperature | 5,800 K |
| Rotational velocity (v sin i) | < 14 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
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