WR 22

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WR 22
Carina Nebula around the Wolf-Rayet star WR 22.jpg
WR 22 in the Carina nebula
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Carina
Right ascension 10h 41m 17.51590s [1]
Declination −59° 40′ 36.8957″ [1]
Apparent magnitude  (V)6.42 [2]
Characteristics
Spectral type WN7h + O9III-V [3]
Apparent magnitude  (U)5.68 [2]
Apparent magnitude  (B)6.50 [2]
Apparent magnitude  (J)5.705 [4]
Apparent magnitude  (H)5.578 [4]
Apparent magnitude  (K)5.389 [4]
U−B color index −0.82 [2]
B−V color index 0.08 [2]
J−H color index 0.127 [4]
J−K color index 0.316 [4]
Variable type Eclipsing binary [5]
Astrometry
Radial velocity (Rv)−28.00 [6]  km/s
Proper motion (μ)RA: −7.321 [7]   mas/yr
Dec.: 3.091 [7]   mas/yr
Parallax (π)0.3953 ± 0.0348  mas [7]
Distance 8,300 ± 700  ly
(2,500 ± 200  pc)
Absolute magnitude  (MV)−6.73 + −4.44 [5]
Orbit [8]
PrimaryWR
CompanionO
Period (P)80.336 days [9]
Semi-major axis (a)330 R☉
Eccentricity (e)0.598
Inclination (i)83.5 [9] °
Argument of periastron (ω)
(secondary)		268.2°
Semi-amplitude (K1)
(primary)		70.6 km/s
Semi-amplitude (K2)
(secondary)		190.0 km/s
Details
WR
Mass 49 - 75 [10]   M☉
Radius 22.65 [10]   R☉
Luminosity 1,905,000 [10]   L☉
Temperature 44,700 [10] [11]   K
O
Mass 25.7 [12]   M☉
Radius 11 [12]   R☉
Luminosity130,000 [12]   L☉
Temperature 33,000 [12]   K
Age 2.2 [11]   Myr
Other designations
CD −59°3221, HR  4188, HD  92740, V429  Carinae, HIP  52308
Database references
SIMBAD data

WR 22, also known as V429 Carinae or HR 4188, is an eclipsing binary star system in the constellation Carina. The system contains a Wolf-Rayet (WR) star that is one of the most massive and most luminous stars known, and is also a bright X-ray source due to colliding winds with a less massive O class companion. Its eclipsing nature and apparent magnitude make it very useful for constraining the properties of luminous hydrogen-rich WR stars. [9]

Contents

In 1978, Anthony Moffat and Wilhelm Seggewiss announced that the star's brightness varies. [13] Eclipses were first detected by Luis A. Balona et al. in 1989. [14] It received its variable star designation, V429 Carinae, in 1980. [15]

System

The WR 22 system contains two massive stars which orbit every 80 days. The spectrum and luminosity are dominated by the primary, which has a spectral type of WN7h, indicating that it is a WR star on the nitrogen sequence, but also with hydrogen lines in its spectrum. The secondary is an O9 star which appears to have the spectral luminosity class of a giant star, but the brightness of a main sequence star. [5]

A blue band light curve for V429 Carinae, showing an eclipse minimum at UT 02:24 on March 8, 1990. Adapted from Gosset et al. (1991) V429CarLightCurve.png
A blue band light curve for V429 Carinae, showing an eclipse minimum at UT 02:24 on March 8, 1990. Adapted from Gosset et al. (1991)

There is a shallow eclipse detectable when the primary passes in front of the secondary, which would be classed as the secondary eclipse. However, no primary eclipse is detected, which is believed to be due to the eccentricity of the system placing the stars further apart when the primary eclipse would occur. [9] The separation of the stars varies from over 500 R☉ to less than 150 R☉. This strongly constrains the possible inclinations of the system. [11]

Properties

The masses of the two stars can be determined fairly accurately because WR 22 is an eclipsing binary. It is one of the most massive star systems measured in this way rather than by assumptions about stellar evolution. Despite this, the dynamical masses derived from orbital fitting vary from over 70 M☉ to less than 60 M☉ for the primary and about 21 - 27 M☉ for the secondary. [8] The spectroscopic mass of the primary has been calculated at 74 M☉ [17] or 78.1 M☉. [11]

The temperature of both stars is high, but somewhat poorly defined. The Wolf Rayet primary has a temperature of approximately 44,700 K derived from a model atmosphere fitting of the spectrum, and the secondary is assumed to have a temperature of 33,000 K which is typical for a star of its spectral type. [12]

The brightness of the two stars cannot be measured separately, but the luminosity ratio can be calculated. The total system absolute magnitude, for a distance of 2.7 kpc and extinction of 1.12 magnitudes, is −6.85. [5] The luminosities calculated for a similar distance are two million L☉ and 130,000 L☉. [11]

Evolution

High mass hydrogen-rich WR stars are young stars still burning hydrogen in their cores, rather than evolved stars fusing heavier elements. They show the WR characteristics of strong helium and nitrogen emission because they are strongly convective all the way to the core and have dredged up fusion products to the surface. About two million years ago, WR22 would have been an even hotter O type main sequence star with a mass of around 120 M☉. It will soon exhaust the hydrogen in its core and evolve into a classical hydrogen-poor WR star, possibly after a period as a luminous blue variable, [11] then explode as a supernova.[ citation needed ] The secondary star is expected to have a more traditional evolution into a red hypergiant in a few million years time.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Wolf–Rayet star</span> Heterogeneous class of stars with unusual spectra

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.

<span class="mw-page-title-main">Westerlund 2</span> Open star cluster in the Carina constellation

Westerlund 2 is an obscured compact young star cluster in the Milky Way, with an estimated age of about one or two million years. It contains some of the hottest, brightest, and most massive stars known. The cluster resides inside a stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina. It is half a degree from the naked eye Cepheid variable V399 Carinae.

<span class="mw-page-title-main">HD 5980</span> Triple star system in the constellation Tucana

HD 5980 is a multiple star system on the outskirts of NGC 346 in the Small Magellanic Cloud (SMC) and is one of the brightest stars in the SMC.

<span class="mw-page-title-main">AB7</span> Binary star in the Small Magellanic Cloud in the constellation Tucana

AB7, also known as SMC WR7, is a binary star in the Small Magellanic Cloud. A Wolf–Rayet star and a supergiant companion of spectral type O orbit in a period of 19.56 days. The system is surrounded by a ring-shaped nebula known as a bubble nebula.

<span class="mw-page-title-main">WR 46</span> Star in the constellation Crux

WR 46 is a Wolf-Rayet star in the constellation of the Southern Cross of apparent magnitude +10.8. It is located at 55 arcmin north of Theta2 Crucis. The star is a member of the distant stellar association Cru OB4, and is around 2,900 parsecs or 9,300 light years from the Solar System.

HD 38282 is a massive spectroscopic binary star in the Tarantula Nebula, consisting of two hydrogen-rich Wolf-Rayet stars.

<span class="mw-page-title-main">WR 24</span> Wolf-Rayet star in the constellation Carina

WR 24 is a Wolf-Rayet star in the constellation Carina. It is one of the most luminous stars known. At the edge of naked eye visibility it is also one of the brightest Wolf Rayet stars in the sky.

<span class="mw-page-title-main">WR 148</span> Binary star in the constellation of Cygnus

WR 148 is a spectroscopic binary in the constellation Cygnus. The primary star is a Wolf–Rayet star and one of the most luminous stars known. The secondary has been suspected of being a stellar-mass black hole but may be a class O main sequence star.

<span class="mw-page-title-main">Melnick 34</span> Binary star in the Large Magellanic cloud

Melnick 34, also called BAT99-116, is a binary Wolf–Rayet star near R136 in the 30 Doradus complex in the Large Magellanic Cloud. Both components are amongst the most massive and most luminous stars known, and the system is the most massive known binary system.

<span class="mw-page-title-main">WR 102</span> Star in the constellation Sagittarius

WR 102 is a Wolf–Rayet star in the constellation Sagittarius, 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.

<span class="mw-page-title-main">CD Crucis</span> Eclipsing binary star system in the constellation Crux

CD Crucis, also known as HD 311884, is an eclipsing binary star system in the constellation Crux. It is around 14,000 light years away near the faint open cluster Hogg 15. The binary contains a Wolf–Rayet star and is also known as WR 47.

<span class="mw-page-title-main">WR 30a</span> Binary star in the constellation Carina

WR 30a is a massive spectroscopic binary in the Milky Way galaxy, in the constellation Carina. The primary is an extremely rare star on the WO oxygen sequence and the secondary a massive class O star. It appears near the Carina Nebula but is much further away.

<span class="mw-page-title-main">WR 137</span> Star in the constellation of Cygnus

WR 137 is a variable Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cygnus.

<span class="mw-page-title-main">WR 1</span> Star in the constellation Cassiopeia

WR 1 is a Wolf-Rayet star located around 10,300 light years away from Earth in the constellation of Cassiopeia. It is only slightly more than twice the size of the sun, but due to a temperature over 100,000 K it is over 758,000 times as luminous as the sun.

WR 3 is a Wolf-Rayet star located around 9,500 light years away from Earth in the constellation of Cassiopeia.

<span class="mw-page-title-main">WR 12</span> Star in the constellation Vela

WR 12 is a spectroscopic binary in the constellation Vela. It is an eclipsing binary consisting of a Wolf-Rayet star and a luminous companion of unknown spectral type. The primary is one of the most luminous stars known.

<span class="mw-page-title-main">WR 9</span> Spectroscopic binary star system in the constellation Puppis

WR 9 is a spectroscopic binary in the constellation Puppis consisting of a Wolf-Rayet star and a class O star. It is around 12,000 light years away.

<span class="mw-page-title-main">HD 151932</span> Star in the constellation of Scorpius

HD 151932, also known as WR 78, is a Wolf-Rayet star located in the constellation Scorpius, close to the galactic plane. Its distance is around 1,300 parsecs away from the Earth. Despite being a blue-colored Wolf-Rayet star, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands. HD 151932 lies about 22′ west of the open cluster NGC 6231, the center of the OB association Scorpius OB1; it is not clear whether it is a part of the association or not. With an apparent magnitude of about 6.5, it is one of the few Wolf-Rayet stars that can be seen with the naked eye.

<span class="mw-page-title-main">HM 1</span> Open cluster in the constellation Scorpius

HM 1, also known as Havlen-Moffat 1, is an open cluster located in the constellation of Scorpius, close to the galactic plane. It was first observed by R. J. Havlen and A. F. J. Moffat in 1976. HM 1 is thought to be 9,500 to 12,700 light-years away from the Earth, beyond the Carina–Sagittarius Arm. It is heavily reddened by interstellar extinction, so although it comprises mostly blue-colored stars, it appears brighter for longer-wavelength passbands. It is projected against the H II region known as RCW 121, and appears to be the source of ionization for the nearby regions RCW 122 and RCW 123.

<span class="mw-page-title-main">WR 120</span> Binary star system in the constellation Scutum

WR 120 is a binary containing two Wolf-Rayet stars in the constellation of Scutum, around 10,000 light years away. The primary is a hydrogen-free weak-lined WN7 star, the secondary is a hydrogen-free WN3 or 4 star, and the system is a possible member of the cluster Dolidze 33. From our point of view, WR 120 is reddened by 4.82 magnitudes, and it has the variable designation of V462 Scuti.

References

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  2. 1 2 3 4 5 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ↑ Gagné, M.; Fehon, G.; Savoy, M. R.; Cartagena, C. A.; Cohen, D. H.; Owocki, S. P. (2012). "An X-Ray Survey of Colliding Wind Binaries". Proceedings of a Scientific Meeting in Honor of Anthony F. J. Moffat Held at Auberge du Lac Taureau. 465: 301. arXiv: 1205.3510 . Bibcode:2012ASPC..465..301G.
  4. 1 2 3 4 5 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  5. 1 2 3 4 Gosset, E.; Nazé, Y.; Sana, H.; Rauw, G.; Vreux, J.-M. (2009). "Phase-resolved XMM-Newton observations of the massive WR+O binary WR 22". Astronomy and Astrophysics. 508 (2): 805. Bibcode:2009A&A...508..805G. doi: 10.1051/0004-6361/20077981 .
  6. ↑ Kharchenko, N. V.; Scholz, R.-D.; Piskunov, A. E.; Röser, S.; Schilbach, E. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv: 0705.0878 . Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID   119323941.
  7. 1 2 3 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.
  8. 1 2 Schweickhardt, J.; Schmutz, W.; Stahl, O.; Szeifert, Th.; Wolf, B. (1999). "Revised mass determination of the super massive Wolf-Rayet star WR 22". Astronomy and Astrophysics. 347: 127. Bibcode:1999A&A...347..127S.
  9. 1 2 3 4 Lenoir-Craig, G.; Antokhin, I. I.; Antokhina, E. A.; St-Louis, N.; Moffat, A F J. (2021). "On the nature of the single eclipse per 80d orbit of the H-rich luminous WN star WR22". Monthly Notices of the Royal Astronomical Society. 510: 246–259. arXiv: 2111.09400 . doi: 10.1093/mnras/stab3374 .
  10. 1 2 3 4 Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J.; Oskinova, L. M. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy & Astrophysics. A57: 625. arXiv: 1904.04687 . Bibcode:2019A&A...625A..57H. doi:10.1051/0004-6361/201834850. S2CID   104292503.
  11. 1 2 3 4 5 6 Gräfener, G.; Hamann, W.-R. (2008). "Mass loss from late-type WN stars and its Z-dependence. Very massive stars approaching the Eddington limit". Astronomy and Astrophysics. 482 (3): 945. arXiv: 0803.0866 . Bibcode:2008A&A...482..945G. doi:10.1051/0004-6361:20066176. S2CID   16025012.
  12. 1 2 3 4 5 Parkin, E. R.; Gosset, E. (2011). "Investigating the X-ray emission from the massive WR+O binary WR 22 using 3D hydrodynamical models". Astronomy & Astrophysics. 530: A119. arXiv: 1104.2383 . Bibcode:2011A&A...530A.119P. doi:10.1051/0004-6361/201016125. S2CID   55645991.
  13. ↑ Moffat, A. F. J.; Seggewiss, W. (November 1978). "The intrinsically bright Wolf-Rayet stars of type WN7. I. The binary HD 92740 and the probable single star HD 93131 in Carina". Astronomy and Astrophysics. 70: 69–78. Bibcode:1978A&A....70...69M . Retrieved 11 January 2025.
  14. ↑ Balona, L. A.; Egan, J.; Marang, F. (September 1989). "Intensive photometry of southern Wolf-Rayet stars". Monthly Notices of the Royal Astronomical Society. 240: 103–115. Bibcode:1989MNRAS.240..103B. doi: 10.1093/mnras/240.1.103 . Retrieved 11 January 2025.
  15. ↑ Kazarovets, E. V.; Samus, N. N. (October 1990). "The 70th Name-List of Variable Star" (PDF). Information Bulletin on Variable Stars. 3530: 1–11. Bibcode:1990IBVS.3530....1K . Retrieved 11 January 2025.
  16. ↑ Gosset, E.; Remy, M.; Manfroid, J.; Vreux, J. M.; Balona, L. A.; Sterken, C.; Franco, G. A. P. (March 1991). "WR 22 is an Eclipsing Binary Star". Information Bulletin on Variable Stars. 3571: 1. Bibcode:1991IBVS.3571....1G . Retrieved 22 November 2021.
  17. ↑ Hamann, W.-R.; Gräfener, G.; Liermann, A. (2006). "The Galactic WN stars. Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation". Astronomy and Astrophysics. 457 (3): 1015. arXiv: astro-ph/0608078 . Bibcode:2006A&A...457.1015H. doi:10.1051/0004-6361:20065052. S2CID   18714731.
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