Delta Circini
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Circinus |
| Right ascension | 15h 16m 56.89591s |
| Declination | −60° 57′ 26.1201″ |
| Apparent magnitude (V) | 5.09 (5.05 - 5.20) |
| Characteristics | |
| Spectral type | O7.5III(f) (O8IV + O9.5V + B0.5V) |
| U−B color index | −0.88 |
| B−V color index | −0.06 |
| Variable type | Eclipsing and ellipsoidal |
| Astrometry | |
| Radial velocity (Rv) | −17.80 km/s |
| Proper motion (μ) | RA: −4.085 mas/yr Dec.: −3.758 mas/yr |
| Parallax (π) | 1.4345±0.1231 mas |
| Distance | 2,641.5 ± 5.9 ly (809.9±1.8 pc) |
| Orbit | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 3.90244719(52) days |
| Semi-major axis (a) | 34.56±0.01 R☉ |
| Eccentricity (e) | 0.06116±0.00010 |
| Inclination (i) | 78.7745±0.0088° |
| Periastron epoch (T) | 58,650.055430±0.00010 RJD |
| Argument of periastron (ω) (secondary) | 344.83±0.37° |
| Semi-amplitude (K1) (primary) | 156.8 km/s |
| Semi-amplitude (K2) (secondary) | 280.4 km/s |
| Orbit | |
| Primary | Aab |
| Name | Ac |
| Period (P) | 1,603.24±0.19 days |
| Semi-major axis (a) | 10.065±0.018 au |
| Eccentricity (e) | 0.5291±0.0011 |
| Inclination (i) | 78.216±0.030° |
| Longitude of the node (Ω) | 256.87±0.07° |
| Argument of periastron (ω) (secondary) | 300.43±0.08° |
| Semi-amplitude (K1) (primary) | 24.37±0.10 km/s |
| Semi-amplitude (K2) (secondary) | 54.42±0.08 km/s |
| Details | |
| Aa | |
| Mass | 23.358±0.030 M☉ |
| Radius | 9.647±0.013 R☉ |
| Luminosity | 153,000+27,000 −23,000 L☉ |
| Surface gravity (log g) | 3.8375±0.0013 cgs |
| Temperature | 33,750±300 K |
| Rotational velocity (v sin i) | 117±5 km/s |
| Age | 4.4±0.1 Myr |
| Ab | |
| Mass | 12.997±0.019 M☉ |
| Radius | 5.3997±0.0076 R☉ |
| Luminosity | 21,827+5,026 −4,085 L☉ |
| Surface gravity (log g) | 4.0871±0.0015 cgs |
| Temperature | 27,500±1,000 K |
| Rotational velocity (v sin i) | 96±10 km/s |
| Age | 4.7±0.2 Myr |
| Ac | |
| Mass | 16.41±0.12 M☉ |
| Radius | 5.79+0.46 −0.42 R☉ |
| Luminosity | 17,000 L☉ |
| Surface gravity (log g) | 4.09±0.06 cgs |
| Temperature | 29,000±2,000 K |
| Age | 4.3+1.1 −1.4 Myr |
| Other designations | |
| δ Cir, CD−60°5539, SAO 253084, HD 135240, HR 5664, HIP 74778, WDS J15169-6057 | |
| Database references | |
| SIMBAD | data |
Delta Circini (δ Cir), is a multiple star system located in the constellation Circinus. Delta Circini is also known as HR 5664, and HD 135240. The system has a combined apparent visual magnitude of +5.09, and is located at a distance of about 700 pc (2,300ly) from the Sun.