Sigma Coronae Borealis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Corona Borealis |
| σ CrB A (σ2) | |
| Right ascension | 16h 14m 40.854s |
| Declination | +33° 51′ 31.02″ |
| Apparent magnitude (V) | 5.55 |
| σ CrB B (σ1) | |
| Right ascension | 16h 14m 40.394s |
| Declination | +33° 51′ 27.05″ |
| Apparent magnitude (V) | 6.419 |
| σ CrB C | |
| Right ascension | 16h 13m 56.26666s |
| Declination | +33° 46′ 24.2953″ |
| Apparent magnitude (V) | 12.229 |
| Characteristics | |
| σ CrB | |
| Spectral type | F6V (A) + G1V (B) |
| U−B color index | +0.045 |
| B−V color index | +0.599 |
| Variable type | RS CVn |
| σ CrB C | |
| Spectral type | M2.5V |
| Astrometry | |
| σ CrB A | |
| Radial velocity (Rv) | −12.30±0.06 km/s |
| Proper motion (μ) | RA: −268.325 mas/yr Dec.: −86.925 mas/yr |
| Parallax (π) | 44.1346±0.0644 mas |
| Distance | 73.9 ± 0.1 ly (22.66 ± 0.03 pc) |
| Absolute magnitude (MV) | +4.02 |
| σ CrB B | |
| Radial velocity (Rv) | −12.30±0.06 km/s |
| Proper motion (μ) | RA: −291.118 mas/yr Dec.: −78.651 mas/yr |
| Parallax (π) | 44.1475 ± 0.0237 mas |
| Distance | 73.88 ± 0.04 ly (22.65 ± 0.01 pc) |
| Absolute magnitude (MV) | +4.64 |
| σ CrB C | |
| Radial velocity (Rv) | −16.30±10 km/s |
| Proper motion (μ) | RA: −265.92 mas/yr Dec.: −83.63 mas/yr |
| Parallax (π) | 42.8557±0.3965 mas |
| Distance | 76.1 ± 0.7 ly (23.3 ± 0.2 pc) |
| Absolute magnitude (MV) | +10.41 |
| Orbit | |
| Primary | σ2 CrB primary |
| Companion | σ2 CrB secondary |
| Period (P) | 1.139791423(80) days |
| Semi-major axis (a) | 1.225±0.013 mas |
| Eccentricity (e) | 0.0 |
| Inclination (i) | 28.08±0.34° |
| Longitude of the node (Ω) | 207.93±0.67° |
| Periastron epoch (T) | 2450127.61845(20) |
| Argument of periastron (ω) (secondary) | 0.0° |
| Orbit | |
| Primary | σ2 CrB |
| Companion | σ1 CrB |
| Period (P) | 726±62 yr |
| Semi-major axis (a) | 5.26±0.35″ |
| Eccentricity (e) | 0.72±0.01 |
| Inclination (i) | 32.3±4.1° |
| Longitude of the node (Ω) | 28.0±0.5° |
| Periastron epoch (T) | B 1825.2±1.5 |
| Argument of periastron (ω) (primary) | 237.3±6.8° |
| Orbit | |
| Primary | σ CrB Ca |
| Companion | σ CrB Cb |
| Period (P) | 52 yr |
| Semi-major axis (a) | 0.111″ |
| Eccentricity (e) | 0.36 |
| Inclination (i) | 59° |
| Longitude of the node (Ω) | 30° |
| Periastron epoch (T) | B 1963.0 |
| Argument of periastron (ω) (secondary) | 127° |
| Details | |
| σ1 CrB | |
| Mass | 1.0 M☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 5,950±100 K |
| Rotational velocity (v sin i) | 3±2 km/s |
| Age | 1 to 3 Myr |
| σ2 CrB primary | |
| Mass | 1.137±0.037 M☉ |
| Radius | 1.244±0.050 R☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 6,050±150 K |
| Metallicity [Fe/H] | 0.0 dex |
| Rotational velocity (v sin i) | 26±1 km/s |
| Age | 0.5 to 1.5 Gyr |
| σ2 CrB secondary | |
| Mass | 1.090±0.036 M☉ |
| Radius | 1.244±0.050 R☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 5,870±150 K |
| Metallicity [Fe/H] | 0.0 dex |
| Rotational velocity (v sin i) | 26±1 km/s |
| Age | 0.5 to 1.5 Gyr |
| σ CrB C | |
| Mass | 0.423±0.042 M☉ |
| Radius | 0.437±0.020 R☉ |
| Surface gravity (log g) | 5.0 cgs |
| Temperature | 3,454±63 K |
| Metallicity [Fe/H] | −0.06±0.03 dex |
| Age | 2.95 Gyr |
| Other designations | |
| σ CrB, 17 CrB, BD+34°2750, GJ 605.2, SAO 65165, ADS 9979, CCDM J16147+3352, WDS J16147+3352 | |
| σ CrB A: σ2 CrB, TZ CrB, GJ 9550A, HD 146361, HIP 79607A, HR 6063, TYC 2583-1846-1 | |
| σ CrB B: σ1 CrB, GJ 9550B, HD 146362, HIP 79607B, HR 6064, TYC 2583-1846-2 | |
| σ CrB C: GJ 9549, HIP 79551, G 180-42 | |
| Database references | |
| SIMBAD | σ CrB |
| σ1 CrB | |
| σ2 CrB | |
| σ CrB C | |
| ARICNS | σ1 CrB |
| σ2 CrB | |
| σ CrB C | |
Sigma Coronae Borealis (σ CrB) is a star system in the constellation of Corona Borealis. It is a quintuple star system containing three sunlike main-sequence stars and two other low-mass stars. The combined visual magnitude is 5.3 and the system lies 74 light years from Earth. σ CrB A is the variable star TZ Coronae Borealis.