WR 142

WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence. It is a luminous and very hot star, highly evolved and close to exploding as a supernova. It is suspected to be a binary star with a companion orbiting about AU away.

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: −6.270[6] mas/yr
Dec.: −3.422[6] mas/yr
Parallax (π)0.5755 ± 0.0284[6] mas
Distance5,700 ± 300 ly
(1,740 ± 90 pc)
Absolute magnitude (MV)−3.13[7]
Details
Mass28.6[7] M
Radius0.80[7] R
Luminosity (bolometric)912,000[7] L
Temperature200,000[7] K
Metallicity [Fe/H]0.0[3] dex
Rotational velocity (v sin i)1,000[2] km/s
Other designations
WR 142, 2MASS J20214434+3722306, GSC 02684-00001, Sand 5, St 3, UCAC2 44891902
Database references
SIMBADdata

Discovery

Location of WR 142, circled (the bright star at the centre is γ Cygni and north is to the right)
Red circle.svg
Location of WR 142, circled (the bright star at the centre is γ Cygni and north is to the right)

In 1966, a search for Wolf-Rayet stars in the northern celestial hemisphere discovered seven new examples. One, designated as Stephenson 3, was classified as WC.[8] It was later found to show unusual emission lines of highly ionised OVI.[9] Because of the unusual oxygen lines, seen in only a handful of other stars, it was given the spectral type WC5pec in the Sixth Catalogue of Galactic Wolf-Rayet Stars.[5]

In 1981, described as a WC-OVI star, it was identified as being associated with the active star-forming region ON2,[10] and then a heavily-obscured open cluster designated Berkeley 87, 9.5 south of the red supergiant BC Cygni.[4]

In 1982, the WC-OVI stars were grouped as members of the new WO class. The class at that time consisted of five stars, two of which were in the Magellanic Clouds and one of which was later found to be the central star of a planetary nebula.[11]

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.[12]

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.[7] 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.[12]

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).[13] It is very likely that WR 142 is on its last stages of nuclear fusion, near or beyond the end of helium burning.[14] 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. ^ a b c d e Zacharias, N.; et al. (2003). "The Second U.S. Naval Observatory CCD Astrograph Catalog (UCAC2)". CDS/ADC Collection of Electronic Catalogues. 1289: 0. Bibcode:2003yCat.1289....0Z.
  2. ^ a b 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.
  3. ^ a b c d Tramper, F.; Straal, S. M.; Sanyal, D.; Sana, H.; de Koter, A.; Gräfener, G.; Langer, N.; Vink, J. S.; de Mink, S. E.; Kaper, L. (2015). "Massive stars on the verge of exploding: The properties of oxygen sequence Wolf-Rayet stars". Astronomy & Astrophysics. 581 (110): A110. arXiv:1507.00839v1. Bibcode:2015A&A...581A.110T. doi:10.1051/0004-6361/201425390.
  4. ^ a b Turner, D. G.; Forbes, D. (1982). "Berkeley 87, a heavily-obscured young cluster associated with the ON2 star-formation complex and containing the WO star Stephenson 3". Publications of the Astronomical Society of the Pacific. 94: 789. Bibcode:1982PASP...94..789T. doi:10.1086/131065. ISSN 0004-6280.
  5. ^ a b Van Der Hucht, Karel A.; Conti, Peter S.; Lundström, Ingemar; Stenholm, Björn (1981). "The Sixth Catalogue of galactic Wolf-Rayet stars, their past and present". Space Science Reviews. 28 (3): 227–306. Bibcode:1981SSRv...28..227V. doi:10.1007/BF00173260. ISSN 0038-6308.
  6. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. ^ a b c d e f Sander, A. A. C.; Hamann, W.-R.; Todt, H.; Hainich, R.; Shenar, T.; Ramachandran, V.; Oskinova, L. M. (2019). "The Galactic WC and WO stars". Astronomy & Astrophysics. 621: A92. arXiv:1807.04293. Bibcode:2019A&A...621A..92S. doi:10.1051/0004-6361/201833712.
  8. ^ Stephenson, C. B. (1966). "Search for new Northern Wolf-Rayet stars". The Astronomical Journal. 71: 477. Bibcode:1966AJ.....71..477S. doi:10.1086/109951.
  9. ^ Sanduleak, N. (1971). "On Stars Having Strong O VI Emission". The Astrophysical Journal. 164: L71. Bibcode:1971ApJ...164L..71S. doi:10.1086/180694.
  10. ^ Pitault, A. (1981). "Possible association of a WC-OVI star with an active site of star formation". Astronomy and Astrophysics. 97: L5. Bibcode:1981A&A....97L...5P.
  11. ^ Barlow, M. J.; Hummer, D. G. (1982). "The WO Wolf-rayet stars". Wolf-Rayet Stars: Observations. 99: 387–392. Bibcode:1982IAUS...99..387B. doi:10.1007/978-94-009-7910-9_51. ISBN 978-90-277-1470-1.
  12. ^ 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...715.1327S. doi:10.1088/0004-637X/715/2/1327.
  13. ^ 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". Astronomy & Astrophysics. 558: A131. arXiv:1308.4681. Bibcode:2013A&A...558A.131G. doi:10.1051/0004-6361/201321906.
  14. ^ 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". Astronomy & Astrophysics. 564: A30. arXiv:1401.7322. Bibcode:2014A&A...564A..30G. doi:10.1051/0004-6361/201322573.
41 Cygni

41 Cygni (41 Cyg) is a star in the constellation Cygnus. Its apparent magnitude is 4.02.

Gliese 806

Gliese 806 is a red dwarf star in the constellation of Cygnus, located roughly 41 light years from the Sun. The star is suspected to host a substellar companion yet unconfirmed.

HD 185435

HD 185435 is a star in the constellation Cygnus. Its apparent magnitude is 6.42.

HD 189276

HD 189276 is a star in the constellation Cygnus. Its apparent magnitude is 4.96.

HD 197036

HD 197036 is a 7th magnitude star in the constellation Cygnus, approximately 2000 light years away from Earth. It is a bluish white subgiant star of the spectral type B5IV, meaning it possesses a surface temperature of 11,000 to 25,000 kelvins. It is therefore hotter, larger, and brighter than our Sun. It can be found within one degree of the star Deneb.

KOI-74

KOI-74 (KIC 6889235) is an eclipsing binary star in the constellation of Cygnus. The primary star is an A-type main-sequence star with a temperature of 9,400 K (9,130 °C; 16,460 °F). It lies in the field of view of the Kepler Mission and was determined to have a companion object in orbit around it which is smaller and hotter than the main star.

Kepler-17

Kepler-17 is main-sequence yellow dwarf star. This star is known to host one exoplanet, Kepler-17b, in orbit around it.

Kepler-18

Kepler-18 is a star with almost the same mass as the Sun in the Cygnus constellation with 3 confirmed planets, announced in 2011.

Kepler-23

Kepler-23 is a star in the northern constellation of Cygnus, the swan, that is orbited by a planet found to be unequivocally within the star's habitable zone. With an apparent visual magnitude of 14.0, this star is too faint to be seen with the naked eye.

Kepler-35

Kepler-35 is a binary star system in the constellation of Cygnus. These stars, called Kepler-35A and Kepler-35B have masses of 89% and 81% solar masses respectively, therefore both are spectral class G. They are separated by 0.176 AU, and complete an eccentric orbit around a common center of mass every 20.73 days.

Kepler-36

Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.

Kepler-44

Kepler-44,formerly known as KOI-204, is a star in the northern constellation of Cygnus. It is located at the celestial coordinates: Right Ascension 20h 00m 24.564s, Declination +45° 45′ 43.71″. With an apparent visual magnitude of 16, this star is too faint to be seen with the naked eye.

Kepler-66

Kepler-66 is a star with slightly more mass than the Sun in the NGC 6811 open cluster in the Cygnus constellation. It has one confirmed planet, slightly smaller than Neptune, announced in 2013.

Kepler-67

Kepler-67 is a star with slightly less mass than the Sun in the NGC 6811 open cluster in the Cygnus constellation and has one confirmed planet, slightly smaller than Neptune, announced in 2013.

List of hottest stars

This is a list of hottest stars so far discovered (excluding degenerate stars), arranged by decreasing temperature. The stars with temperatures higher than 60,000 K are included.

V1057 Cygni

V1057 Cygni (V1057 Cyg) is a FU Orionis-type variable star in the constellation of Cygnus. It has a spectral type of F and an apparent visual magnitude of approximately 11.660. It was the second FU Orionis-type variable discovered.

V1668 Cygni

V1668 Cygni was a nova that appeared in the constellation Cygnus in 1978 with a maximum brightness of 6th apparent magnitude.

V1974 Cygni

V1974 Cygni or Nova Cygni 1992 was a relatively bright nova in the constellation Cygnus.

It was discovered on February 19, 1992, by Peter Collins. At that time it was magnitude 6, the maximum magnitude reached was 4.4. The hydrogen burning on the white dwarf ended two years later, in 1994. This nova was a neon nova. It is the first nova observed from onset to completion, and can be calculated to be 10,430 light years away from Earth.

It was also studied with the Hubble Space Telescope instrument the High Speed Photometer. The instrument recorded a short amount of ultraviolet photometry. The nova was also observed in the far-ultraviolet by Voyager 2.

V476 Cygni

V476 Cygni or Nova Cygni 1920 was a nova which occurred in the constellation Cygnus in 1920. It reached a brightness of 2.0 mag. Nowadays its brightness is 17.09 mag.

Stars
Star
clusters
Molecular
clouds
Nebulae
Galaxies

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.