NU Orionis
Image of Messier 43, with NU Orionis in the center | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 31.3649s |
| Declination | −05° 16′ 02.582″ |
| Apparent magnitude (V) | +6.80–6.93 |
| Characteristics | |
| Spectral type | B0.5V (Aa) + A/B (B) + B2V (C) |
| Variable type | INSA |
| Astrometry | |
| Radial velocity (Rv) | 67±1 km/s |
| Proper motion (μ) | RA: +0.922 mas/yr Dec.: +1.718 mas/yr |
| Parallax (π) | 2.4059±0.0585 mas |
| Distance | 1,360 ± 30 ly (420 ± 10 pc) |
| Orbit | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 14.3027(7) days |
| Semi-major axis (a) | 0.36±0.01 au |
| Eccentricity (e) | <0.02 |
| Inclination (i) | 70±4° |
| Periastron epoch (T) | 2,440,578.5(5) JD |
| Semi-amplitude (K1) (primary) | 50±8 km/s |
| Semi-amplitude (K2) (secondary) | 172±3 km/s |
| Orbit | |
| Primary | A |
| Name | C |
| Period (P) | 476±1 days |
| Semi-major axis (a) | 3.77±0.12 au |
| Eccentricity (e) | 0.09±0.06 |
| Inclination (i) | 70.1±0.9° |
| Periastron epoch (T) | 2,453,639(7) JD |
| Argument of periastron (ω) (secondary) | 100±5° |
| Semi-amplitude (K1) (primary) | 21±4 km/s |
| Semi-amplitude (K2) (secondary) | 47±6 km/s |
| Position (relative to AC) | |
| Component | B |
| Epoch of observation | 1999 |
| Angular distance | 470 mas |
| Projected separation | 195±4 AU |
| Details | |
| Aa | |
| Mass | 16.4±0.4 M☉ |
| Radius | 5.7±0.3 R☉ |
| Luminosity | 26,900 L☉ |
| Surface gravity (log g) | 4.15±0.05 cgs |
| Temperature | 31,100±500 K |
| Rotational velocity (v sin i) | 190±20 km/s |
| Age | 3+2 −1 Myr |
| Ab | |
| Mass | 4.4±0.2 M☉ |
| Radius | 2.5±0.3 R☉ |
| Luminosity | 350 L☉ |
| Surface gravity (log g) | 4.28±0.10 cgs |
| Temperature | 15,700±500 K |
| Rotational velocity (v sin i) | 8±3 km/s |
| Age | 3+2 −1 Myr |
| B | |
| Mass | 3.8 M☉ |
| Radius | 2.3 R☉ |
| Luminosity | 190 L☉ |
| Surface gravity (log g) | 4.28 cgs |
| Temperature | 14,000 K |
| Rotational velocity (v sin i) | 180 km/s |
| Age | 3+2 −1 Myr |
| C | |
| Mass | 8.1±0.4 M☉ |
| Radius | 3.6±0.4 R☉ |
| Luminosity | 2,800 L☉ |
| Surface gravity (log g) | 4.25±0.10 cgs |
| Temperature | 22,300±500 K |
| Rotation | 1.09468(7) days |
| Rotational velocity (v sin i) | 104±10 km/s |
| Age | 3+2 −1 Myr |
| Other designations | |
| BD−05°1325, HD 37061, HIP 26258, TYC 4774-906-1 | |
| Database references | |
| SIMBAD | data |
NU Orionis (HD 37061) is a quadruple star system in the Orion constellation. It is located in the emission nebula Messier 43 and is the main star ionizing it. The distance to the system is 1,360 light-years (420 parsecs), as determined by its stellar parallax.