WR 142
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 21m 44.3s[1] |
| Declination | +37° 22′ 30.56″[1] |
| Apparent magnitude (V) | 12.94[2] |
| Characteristics | |
| Spectral type | WO2[3] |
| Apparent magnitude (J) | 9.538[1] |
| Apparent magnitude (H) | 8.889[1] |
| Apparent magnitude (K) | 8.596[1] |
| U−B color index | −0.29[4] |
| B−V color index | +1.43[5] |
| Astrometry | |
| Proper motion (μ) | RA: −8.0 ± 5.4[1] mas/yr Dec.: −.8 ± 5.4[1] mas/yr |
| Distance | 4,000 ly (1,230[2] pc) |
| Absolute magnitude (MV) | -2.49[2] |
| Details | |
| Mass | 20[2] M☉ |
| Radius | 0.40[3] R☉ |
| Luminosity (bolometric) | 245,000[3] L☉ |
| Luminosity (visual, LV) | 847[2] L☉ |
| Temperature | 200,000[3] K |
| Metallicity [Fe/H] | 0.0[3] dex |
| Rotational velocity (v sin i) | 1,000[2] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence.
Features
WR 142 is usually assumed to be a member of the open cluster Berkeley 87, whose distance from the Sun is not very well known but thought to be around 1.23 kiloparsecs (4,000 light-years). As with its home cluster its light is very reddened and extinguished by interstellar dust.[6]
This star, of spectral classification WO2, is one of the very few known oxygen-sequence Wolf-Rayet stars, just four in the Milky Way galaxy and five in external galaxies. It is also one of the hottest known with a surface temperature of 200,000 K.[3] Modelling the atmosphere gives a luminosity around 245,000 L☉, while calculations from brightness and distance give luminosities of 500,000 L☉or more. It is a very small dense star, with a radius 40% of the Sun's but a mass 20 times greater. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 142 to lose 10−5 M☉/year.[2] For comparison, the Sun loses (2-3) x 10−14 solar masses per year due to its solar wind, several hundred million times less than WR 142.
Hard X-Ray emission has been detected from this star with the help of the Chandra space telescope, that has been suggested to be caused by the presence of a companion, a B-type main sequence star located at a distance of 1 AU from WR 142. There is no other indication of a companion and other reasons for the x-ray luminosity are considered more likely.[6]
Evolutionary status
WO Wolf-Rayet stars are the last evolutionary stage of the most massive stars before exploding as supernovae, possibly with a gamma-ray burst (GRB).[7] It is very likely that WR 142 is on its last stages of nuclear fusion, near or beyond the end of helium burning.[8] It is estimated to explode as a supernova in approximately 2,000 years. The mass and rapid rotation make a GRB likely.[3]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
