WR 142

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WR 142

Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 20h 21m 44.3s[1]
Declination +37° 22′ 30.56″
Apparent magnitude (V) 12.96
Spectral type WO2
B−V color index 1.43
Proper motion (μ) RA: -8.0 mas/yr
Dec.: -2.8 mas/yr
Distance 4,000 ly
(1,230 pc)
Absolute magnitude (MV) -2.49
Mass 20 M
Radius 0.59 R
Luminosity (bolometric) 501,000 L
Temperature 200,000 K
Other designations
2MASS J20214434+3722306, GEN# +5.00870029, GSC 02684-00001, Sand 5, St 3, UCAC2 44891902, WR 142.
Database references

WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare member of the WO oxygen sequence.


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 assumed to be around 1.23 kiloparsecs (4,000 light-years). As with its home cluster it's light is very reddened and extinguished by interstellar dust.[2]

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 the hottest known with a surface temperature of 200,000 K (the newest WO discovery may have a similar temperature[3]). The luminosity is 500,000 times that of our Sun and it is very small and dense, with a radius 60% of the solar one but 20 times more massive than our star. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 142 to lose 1.03 × 10−5 solar masses of mass per year.[4] (for comparison, the Sun loses (2-3) x 10−14 solar masses per year (i.e.: several hundred million times less) due to its solar wind).

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.[2]

Evolutionary status[edit]

It's assumed oxygen-rich Wolf-Rayet stars are the last evolutionary stage of the most massive stars before exploding as supernovae or even as Gamma-ray bursts,[5] thus it's very likely WR 142 is on its last stages of nuclear fusion on its core having left behind or being very close to end the helium burning phase and even staying on the carbon burning phase,[6] its fate to explode as a supernova or as a GRB being very close in astronomical terms.

See also[edit]

List of supernova candidates


  1. ^ http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=WR+142&submit=SIMBAD+search SIMBAD Astronomical Database
  2. ^ a b Sokal, Kimberly R.; Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner (2010). "Chandra Detects the Rare Oxygen-type Wolf-Rayet Star WR 142 and OB Stars in Berkeley 87". The Astrophysical Journal 715 (2): 1327–1337. arXiv:1004.0462. Bibcode:2010ApJ...715.1327S9022. doi:10.1088/0004-637X/715/2/1327. 
  3. ^ Massey, Philip (2014). "A MODERN SEARCH FOR WOLF-RAYET STARS IN THE MAGELLANIC CLOUDS: FIRST RESULTS". The Astrophysical Journal 788 (1): 83. doi:10.1088/0004-637X/788/1/83.  edit
  4. ^ Sander, A.; Hamann, W. -R.; Todt, H. (2012). "The Galactic WC stars". Astronomy & Astrophysics 540: A144. arXiv:1201.6354. Bibcode:2012A&A...540A.144S. doi:10.1051/0004-6361/201117830.  edit
  5. ^ Groh, Jose H.; Meynet, Georges; Georgy, Cyril; Ekstrom, Sylvia (2013). "Fundamental properties of core-collapse Supernova and GRB progenitors: Predicting the look of massive stars before death". arXiv:1308.4681v1 [astro-ph.SR]. 
  6. ^ Groh, Jose (2014). "The evolution of massive stars and their spectra I. A non-rotating 60 Msun star from the zero-age main sequence to the pre-supernova stage". arXiv:1401.7322 [astro.ph].