Theta1 Orionis C
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 16.5s |
| Declination | −05° 23′ 24″ |
| Apparent magnitude (V) | 5.13 |
| Characteristics | |
| Spectral type | O6pe V |
| U−B color index | −0.88 |
| B−V color index | +0.02 |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | +28 km/s |
| Proper motion (μ) | RA: −0.92 mas/yr Dec.: 0.13 mas/yr |
| Parallax (π) | −1.85 ± 2.12 mas |
| Distance | 1,500 ly (460 pc) |
| Absolute magnitude (MV) | −3.2 |
| Details | |
| Mass | 40 M☉ |
| Radius | ? R☉ |
| Luminosity | 210,000 L☉ |
| Temperature | 40,000 K |
| Metallicity | ? |
| Rotation | ~112 km/s |
| Age | 1.2 × 106 years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Theta1 Orionis C is a member of the Trapezium open cluster that lies within the Orion Nebula. The star C is the most massive of the four bright stars at the heart of the cluster. It has the highest surface temperature of any star visible to the naked eye and is one of the most luminous stars known (it has an estimated absolute magnitude in visible wavelengths of about −3.2). Its high luminosity and large distance (about 1,500 light years) give it an apparent visible magnitude is 5.1.
This star is responsible for generating most of the ultraviolet light that is slowly ionizing (and perhaps photo evaporating) the Orion Nebula. This UV light is also the primary cause of the glow that illuminates the Orion Nebula. This star emits a powerful stellar wind that is a hundred thousand times stronger than the Sun's, and the outpouring gas moves at 1,000 km/s.
Infrared observations of this star have shown that it is actually a close binary system. It also displays optical variability and is a variable X-ray source.
It is expected that this star will end its life as a supernova within a few million years from now.
References
- Walborn, N. R., 1981, "Systematic variations in the spectrum of Theta-1 Orionis C", Astrophysical Journal, vol. 243, p. L37-L39.
- Gagne, Marc et al, 1997, "Periodic X-Ray Emission from the O7 V Star theta 1 Orionis C", Astrophysical Journal Letters, v.478, p.L87.
External links
- Theta-1 Orionis by Professor Jim Kaler.
- SIMBAD entry