Alpha Coronae Borealis (α Coronae Borealis, abbreviated Alpha CrB, α CrB), officially named Alphecca ,[9] 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.
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
Alpha Coronae Borealis
Location of α Coronae Borealis (circled) |
Observation data Epoch J2000 Equinox J2000 |
Constellation |
Corona Borealis |
Right ascension |
15h 34m 41.268s[1] |
Declination |
+26° 42′ 52.89″[1] |
Apparent magnitude (V) |
2.24[2] |
Characteristics |
Spectral type |
A0V + G5V[3] |
U−B color index |
−0.03[4] |
B−V color index |
−0.02[4] |
Variable type |
Eclipsing binary[5] |
Astrometry |
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Radial velocity (Rv) | +1.7[6] km/s |
Proper motion (μ) | RA: 120.27[1] mas/yr Dec.: −89.58[1] mas/yr |
Parallax (π) | 43.46 ± 0.28 mas[1] |
Distance | 75.0 ± 0.5 ly (23.0 ± 0.1 pc) |
Absolute magnitude (MV) | +0.16/+5.05[3] |
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Orbit[7] |
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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 |
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α CrB A |
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Mass | 2.58[3] M☉ |
Radius | 2.89–3.04[3][7] R☉ |
Luminosity | 74[3] L☉ |
Surface gravity (log g) | 3.89[3] cgs |
Temperature | 9,700[3] K |
Rotational velocity (v sin i) | 139[8] km/s |
Age | 0.314 Gyr |
α CrB B |
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Mass | 0.92[3] M☉ |
Radius | 0.90[3][7] R☉ |
Luminosity | 0.81[3] L☉ |
Surface gravity (log g) | 4.50[3] cgs |
Temperature | 5,800[3] K |
Rotational velocity (v sin i) | < 14[7] km/s |
Other designations |
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Gemma, Alphecca, Ashtaroth, Gnosia Stella Coronae, 5 CrB, BD +27°2512, GCTP 3519.00, FK5 578, HD 139006, HIP 76267, HR 5793, SAO 83893. |
Database references |
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SIMBAD | data |
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