WR 20a

Last updated
WR 20a
NASA Unveils Celestial Fireworks as Official Hubble 25th Anniversary Image.jpg
Cercle jaune 100%25.svg
WR 20a (circled) near Westerlund 2
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team
Observation data
Epoch J2000       Equinox J2000
Constellation Carina
Right ascension 10h 23m 58.002s [1]
Declination −57° 45′ 48.99″ [1]
Apparent magnitude  (V)13.28 [2]
Characteristics
Evolutionary stage Hot slash star [3]
Spectral type O3If*/WN6 + O3If*/WN6 [4]
U−B color index +0.29 [2]
B−V color index +1.63 [2]
Variable type β Lyr + WR [5]
Astrometry
Proper motion (μ)RA: −5.391 [6]   mas/yr
Dec.: 2.949 [6]   mas/yr
Parallax (π)0.2310 ± 0.0171  mas [6]
Distance 14,000 ± 1,000  ly
(4,300 ± 300  pc)
Absolute magnitude  (MV)−6.49 / −6.49 [2]
Orbit [7]
Period (P)3.675 days
Semi-major axis (a)26 R☉
Eccentricity (e)0
Semi-amplitude (K1)
(primary)		353.1 km/s
Semi-amplitude (K2)
(secondary)		362.6 km/s
Details [2]
Primary
Mass 82.7±5.5  M☉
Radius 19.3±0.5  R☉
Luminosity 1,150,000±150,000  L☉
Surface gravity (log g)3.8  cgs
Temperature 43,000±2,000  K
Secondary
Mass 81.9±5.5  M☉
Radius 19.3±0.5  R☉
Luminosity1,150,000±150,000  L☉
Surface gravity (log g)3.8  cgs
Temperature 43,000±2,000  K
Other designations
V712  Carinae, THA  35-II-36, Westerlund 2  MSP 240, 2MASS  J10235800-5745489, UBV M  40466, Westerlund 2  4
Database references
SIMBAD data

WR 20a is an eclipsing binary star belonging to or recently (0.5 millions years before present) ejected from the young, massive cluster Westerlund 2. [8] It was discovered in 2004 to be one of the most massive binary systems known, for which the masses of the components have been accurately measured. [7]

Each star in the system has about eighty times the mass of the Sun. [7] [9] It is not clear why this system is located away from the center of the cluster. It is possible that the system was formed in the core, but that it was ejected by dynamical interactions.

A visual band light curve for WR 20a (V712 Carinae), adapted from Kochanek et al. (2017) V712CarLightCurve.png
A visual band light curve for WR 20a (V712 Carinae), adapted from Kochanek et al. (2017)

Every 3.6 days the two stars in this system revolve around each other. Although the stars are in a very tight orbit, both stars in the system are detached. [11] The two stars eclipse each other on each orbit, producing a drop in brightness of about 0.4 magnitudes. The brightness is also continuously variable outside the eclipses due to the distorted shapes of the two stars. [9] The primary and secondary minima are almost the same depth since the size and temperature of each star is almost identical. [2]

It is expected that within a million years the two will expand and come into contact. A large nitrogen abundance has been measured on the surface of the stars, [2] about six times the abundance of nitrogen measured in the sun. This nitrogen is probably produced in deeper layers of the star and pushed towards the surface by rotational mixing.

A collision between the two winds of the systems has been detected in the visible as well as in X-rays. [2] [12] The X-ray emitting region is quite extended since it does not suffer from any eclipse.

See also

Related Research Articles

<span class="mw-page-title-main">Beta Lyrae</span> Multiple star system in the constellation of Lyra

Beta Lyrae officially named Sheliak, the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 960 light-years distant from the Sun.

<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">Westerlund 1</span> Super star cluster in the Milky Way Galaxy

Westerlund 1 is a compact young super star cluster about 3.8 kpc away from Earth. It is thought to be the most massive young star cluster in the Milky Way, and was discovered by Bengt Westerlund in 1961 but remained largely unstudied for many years due to high interstellar absorption in its direction. In the future, it will probably evolve into a globular cluster.

<span class="mw-page-title-main">Cygnus OB2-8A</span> Spectroscopic binary star near the center of Cygnus OB2

Cygnus OB2 #8A is a double-lined spectroscopic binary located near the centre of the Cygnus OB2 association located 5,500 light years away.

<span class="mw-page-title-main">4U 1700-37</span>

4U 1700-37 is one of the stronger binary X-ray sources in the sky, and is classified as a high-mass X-ray binary. It was discovered by the Uhuru satellite. The "4U" designation refers to the fourth Uhuru catalog.

<span class="mw-page-title-main">HD 150136</span> Multiple star system in the constellation Ara

HD 150136 is a multiple star system in the southern constellation of Ara, around 4,300 light years away. It is the brightest member of the faint open cluster NGC 6193, part of the Ara OB1 association.

<span class="mw-page-title-main">R Arae</span> Variable star in the constellation Ara

R Arae is an Algol-type eclipsing binary in the constellation Ara. Located approximately 298 parsecs (970 ly) distant, it normally shines at magnitude 6.17, but during eclipses can fall as low as magnitude 7.32. It has been suggested by multiple studies that mass transfer is occurring between the two stars of this system, and the period of eclipses seems to be increasing over time. The primary is a blue-white main sequence star of spectral type B5V that is 5 times as massive as the Sun, while the secondary is a yellow-white star of spectral type F1IV that is 1.5 times as massive as the Sun. Stellar material is being stripped off the secondary and accreting on the primary.

<span class="mw-page-title-main">WR 22</span> Binary star in the constellation Carina

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.

<span class="mw-page-title-main">WR 25</span> Binary star system in the constellation Carina

WR 25 is a binary star system in the turbulent star-forming region the Carina Nebula, about 6,800 light-years from Earth. It contains a Wolf-Rayet star and a hot luminous companion and is a member of the Trumpler 16 cluster. The name comes from the Catalogue of Galactic Wolf–Rayet Stars.

<span class="mw-page-title-main">V3903 Sagittarii</span> Binary star system in the constellation Sagittarius

V3903 Sagittarii is an eclipsing binary star system in the constellation Sagittiarus. It creates an H II region LBN 29 1,070 parsecs away from the Sun.

<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">HD 15558</span> Star in the constellation Cassiopeia

HD 15558 is a massive O-type multiple star system in Cassiopeia and is specifically in our galaxy's Heart Nebula in open cluster IC 1805. The primary is a very massive star with 152 M☉ and 660,000 L☉.

<span class="mw-page-title-main">WR 21a</span> Star in the constellation Carina

WR 21a is an eclipsing binary star in the constellation Carina. It includes one of the most massive known stars and is one of the most massive binaries.

<span class="mw-page-title-main">Westerlund 1-20</span> Red supergiant star located in the Westerlund 1 super star cluster

Westerlund 1-20 (abbreviated to Wd 1-20 or just W20) is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 965 solar radii (6.72 × 108 km, 4.48 au), making it one of the largest stars discovered so far. This corresponds to a volume 899 million times bigger than the Sun. If placed at the center of the Solar System, the photosphere of Westerlund 1-20 would almost reach the orbit of Jupiter.

<span class="mw-page-title-main">Westerlund 1-75</span> Red supergiant in the Westerlund 1 super star cluster

Westerlund 1-75 or Wd 1-75 is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius is calculated to be around 668 solar radii (4.65 × 108 km, 3.10 au). This corresponds to a volume 298 million times bigger than the Sun. If placed at the center of the Solar System, Westerlund 1-75 would engulf the inner limits of the asteroid belt.

<span class="mw-page-title-main">DH Cephei</span> Binary star system in the constellation Cepheus

DH Cephei is a variable binary star system in the northern circumpolar constellation of Cepheus, positioned about two degrees to the east of the star system Delta Cephei. With an apparent visual magnitude of 8.61, it is too faint to be visible without a telescope. Based on parallax measurements, this system is located at a distance of approximately 9.6 kilolight-years from the Sun. At present it is moving closer to the Earth with a radial velocity of −33 km/s.

<span class="mw-page-title-main">Westerlund 1-243</span> Luminous blue variable star undergoing an eruptive phase in Westerlund 1

Westerlund 1-243 or Wd 1-243 is a luminous blue variable (LBV) star undergoing an eruptive phase located within the outskirts of the super star cluster Westerlund 1. Located about 13,400 ly (4,100 pc) from Earth, it has a luminosity of 0.73 million L☉ making it one of the most luminous stars known.

<span class="mw-page-title-main">RS Sagittarii</span> Eclipsing binary star system in the constellation Sagittarius

RS Sagittarii is an eclipsing binary star system in the southern constellation of Sagittarius, abbreviated RS Sgr. It is a double-lined spectroscopic binary with an orbital period of 2.416 days, indicating that the components are too close to each other to be individually resolved. The system has a combined apparent visual magnitude of 6.01, which is bright enough to be faintly visible to the naked eye. During the primary eclipse the brightness drops to magnitude 6.97, while the secondary eclipse is of magnitude 6.28. The distance to this system is approximately 1,420 light years based on parallax measurements.

References

  1. 1 2 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.
  2. 1 2 3 4 5 6 7 8 Rauw; et al. (4 March 2005). "The spectrum of the very massive binary system WR 20a (WN6ha + WN6ha): Fundamental parameters and wind interactions" (PDF). Astronomy & Astrophysics. 432 (3): 985–998. Bibcode:2005A&A...432..985R. doi: 10.1051/0004-6361:20042136 .
  3. ↑ Crowther, Paul A.; Walborn, Nolan R. (2011). "Spectral classification of O2-3.5 If*/WN5-7 stars". Monthly Notices of the Royal Astronomical Society. 416 (2): 1311. arXiv: 1105.4757 . Bibcode:2011MNRAS.416.1311C. doi:10.1111/j.1365-2966.2011.19129.x. S2CID   118455138.
  4. ↑ Roman-Lopes, A. (2013). "An O2 If*/WN6 star caught in the act in a compact H II region in the starburst cluster NGC 3603". Monthly Notices of the Royal Astronomical Society. 433 (1): 712–718. arXiv: 1305.0851 . Bibcode:2013MNRAS.433..712R. doi:10.1093/mnras/stt762. S2CID   118367798.
  5. ↑ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. 1 2 3 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  7. 1 2 3 Rauw; et al. (3 June 2004). "WR20a: a massive cornerstone binary system comprising two extreme early-type stars". Astronomy & Astrophysics. 420 (2): L9–L13. arXiv: astro-ph/0404551 . Bibcode:2004A&A...420L...9R. doi:10.1051/0004-6361:20040150. S2CID   119426384.
  8. ↑ Rate, Gemma; Crowther, Paul A.; Parker, Richard J. (2020), "Unlocking Galactic Wolf–Rayet stars with Gaia DR2 – II. Cluster and association membership", Monthly Notices of the Royal Astronomical Society, 495: 1209–1226, arXiv: 2005.02533 , doi:10.1093/mnras/staa1290
  9. 1 2 Bonanos, A. Z.; Stanek, K. Z.; Udalski, A.; Wyrzykowski, L.; Żebruń, K.; Kubiak, M.; Szymański, M. K.; Szewczyk, O.; Pietrzyński, G.; Soszyński, I. (2004). "WR 20a is an Eclipsing Binary: Accurate Determination of Parameters for an Extremely Massive Wolf-Rayet System". The Astrophysical Journal. 611 (1): L33–L36. arXiv: astro-ph/0405338 . Bibcode:2004ApJ...611L..33B. doi:10.1086/423671. S2CID   119479873.
  10. ↑ Kochanek, C. S.; Shappee, B. J.; Stanek, K. Z.; Holoien, T. W.-S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Shields, J. V.; Will, D.; Britt, C.; Perzanowski, D.; Pojmański, G. (October 2017). "The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0". Publications of the Astronomical Society of the Pacific. 129 (980): 104502. arXiv: 1706.07060 . Bibcode:2017PASP..129j4502K. doi: 10.1088/1538-3873/aa80d9 .
  11. ↑ Rauw; et al. (1 March 2007). "Early-type stars in the core of the young open cluster Westerlund 2". Astronomy & Astrophysics. 463 (3): 981–991. arXiv: astro-ph/0612622 . Bibcode:2007A&A...463..981R. doi:10.1051/0004-6361:20066495. S2CID   17776145.
  12. ↑ Naze; et al. (1 May 2008). "Chandra monitoring of the very massive binary WR20a and the young massive cluster Westerlund 2". Astronomy & Astrophysics. 483 (1): 171–182. arXiv: 0801.0647 . Bibcode:2008A&A...483..171N. doi:10.1051/0004-6361:20078851. S2CID   17739235.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.