WR 46

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WR 46
Crux.jpg
Cercle vert 100%25.svg
WR 46 (location circled) in the constellation Crux
Observation data
Epoch J2000       Equinox J2000
Constellation Crux
Right ascension 12h 05m 18.72028s [1]
Declination −62° 03′ 10.1280″ [1]
Apparent magnitude  (V)10.83 [2]
Characteristics
Spectral type WN3p-w [3]
U−B color index -0.84 [2]
B−V color index -0.03 [2]
Variable type Irregular [4]
Astrometry
Radial velocity (Rv)4.00 [5]  km/s
Proper motion (μ)RA: -5.625 [6]   mas/yr
Dec.: 0.304 [6]   mas/yr
Parallax (π)0.3501 ± 0.0343  mas [6]
Distance 9,300 ± 900  ly
(2,900 ± 300  pc)
Absolute magnitude  (MV)−2.56 [3]
Details
Mass 14 [3]   M☉
Radius 1.36 [3]   R☉
Luminosity 263,000 [3]   L☉
Temperature 112,200 [3]   K
Other designations
HD  104994, HIP  58954, DI  Crucis, CD-61°3331, GSC  08978-02316, 2MASS  J12051871-6203101, AAVSO  1200-61
Database references
SIMBAD data

WR 46 (DI Crucis) 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.

Contents

Features

WR 46 has spectral type WN3, with peculiarities in the spectrum including unusually broad emission lines. Its spectrum is characterized by the presence of strong lines of NV and HeII and the absence of hydrogen lines. It is known as a weak-lined WNE star because of the high temperature but relatively weak emission strength. [4]

The physical parameters of WR 46 are all estimates from assumptions about the distance and models for stars of its type, complicated by the suspicion that there is a companion star. The effective temperature is over 110,000K, the luminosity greater than 200,000 times the solar luminosity (L☉), the mass around 14 times that of the Sun (M☉) and a radius of 1.36 times the solar radius (R☉). The terminal velocity of the stellar wind reaches 2450 km/s with a total mass loss rate of 4 × 10−6M☉ per year.

WR 46 is a known source of X-rays, an aspect that was discovered by the Einstein Observatory. [7] The X-ray luminosity between 0.2 and 10.0 keV is 7.7 × 1032 erg/s. Its X-ray spectrum is dominated by a soft component but there is also a hard component above 3 keV (a hard tail).

Variability

A visual band light curve for DI Crucis, adapted from Oliveira et al. (2004) DICruLightCurve.png
A visual band light curve for DI Crucis, adapted from Oliveira et al. (2004)

WR 46 exhibits complex variability on relatively short time scales of a few hours. In the past there have been regular but intermittent changes in the radial velocity, multiple periods and photometric variation at some wavelengths, particularly ultraviolet. It has been proposed that this short-term behavior is due to non-radial pulsations, fast rotational modulation, or the presence of a lower-mass companion. [9] Theories that are now discounted include WR 46 being a Super soft X-ray source [10] or a V Sagittae star, [11]

The radial velocity changes of the spectral lines originating most deeply within the stellar wind show clear radial velocity variations with a period of 7.9 hours. However the lines do not change their shape or intensity, which would be expected from a pulsating star [12] Non-radial pulsations have been proposed, with multiple pulsation periods of varying amplitude accounting for the apparently irregular brightness changes. [4]

Binary star

WR 46 has been suspected to be a binary system with an OB companion. The orbital period of the system has been reported at 0.311 days [10] and 0.329 days. [13] Most recent research refutes the idea of a companion, instead favoring the single WN star theory. [14]

Related Research Articles

<span class="mw-page-title-main">WR 136</span> Star in the constellation of Cygnus

WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as a supernova.

<span class="mw-page-title-main">EZ Canis Majoris</span> Binary star system in the constellation Canis Major

EZ Canis Majoris is binary system in the constellation of Canis Major. The primary is a Wolf-Rayet star and it is one of the ten brightest Wolf-Rayet stars, brighter than apparent magnitude 7.

<span class="mw-page-title-main">WR 7</span> Star in the constellation Canis Major

WR 7 is a Wolf–Rayet star in the constellation of Canis Major. It lies at the centre of a complex bubble of gas which is shocked and partially ionised by the star's radiation and winds.

<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">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 124</span> Star in the constellation Sagitta

WR 124 is a Wolf–Rayet star in the constellation of Sagitta surrounded by a ring nebula of expelled material known as M1-67. It is one of the fastest runaway stars in the Milky Way with a radial velocity around 200 km/s. It was discovered by Paul W. Merrill in 1938, identified as a high-velocity Wolf–Rayet star. It is listed in the General Catalogue of Variable Stars as QR Sagittae with a range of 0.08 magnitudes.

<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">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.

WR 147 is a multiple star system in the constellation of Cygnus. The system is extremely reddened by interstellar extinction - that is, dust in front of the star scatters much of the blue light coming from WR 147, leaving the star appearing reddish.

<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">WR 134</span> Star in the constellation of Cygnus

WR 134 is a variable Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cygnus, surrounded by a faint bubble nebula blown by the intense radiation and fast wind from the star. It is five times the radius of the sun, but due to a temperature over 63,000 K it is 400,000 times as luminous as 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">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">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">HD 152408</span> Star in the constellation of Scorpius

HD 152408, also known as WR 79a, is a Wolf-Rayet star located in the constellation Scorpius, close to the galactic plane. Its distance is around 2,020 parsecs away from the Earth.

<span class="mw-page-title-main">WR 128</span> Wolf-Rayet star in the constellation Sagitta

WR 128 is a Wolf–Rayet star located about 9,500 light years away in the constellation of Sagitta. A member of the WN class, WR 128's spectrum resembles that of a WN4 star, but hydrogen is clearly present in the star, making it the only known hydrogen-rich WN4 star in the galaxy. However, similar H-rich very early WN stars can be found in the LMC and especially in the SMC, but the only other galactic examples of this are WR 3 and WR 152.

WR 138a is a Wolf-Rayet star in the constellation Cygnus. It is of a very late spectral type of WN9h. The WR is also at the centre of a ring nebula and is a runaway.

References

  1. 1 2 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600.
  2. 1 2 3 Reed, B. Cameron (2003). "Catalog of Galactic OB Stars". The Astronomical Journal. 125 (5): 2531–2533. Bibcode:2003AJ....125.2531R. doi: 10.1086/374771 . ISSN   0004-6256.
  3. 1 2 3 4 5 6 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.
  4. 1 2 3 Hénault-Brunet, V.; St-Louis, N.; Marchenko, S. V.; Pollock, A. M. T.; Carpano, S.; Talavera, A. (2011). "New Constraints on the Origin of the Short-Term Cyclical Variability of the Wolf-Rayet Star Wr 46". The Astrophysical Journal. 735 (1): 13. arXiv: 1104.4497 . Bibcode:2011ApJ...735...13H. doi:10.1088/0004-637X/735/1/13. S2CID   119234575.
  5. ↑ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv: astro-ph/0406573 . Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. ISSN   0004-6361. S2CID   119387088.
  6. 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.
  7. ↑ Pollock, A. M. T. (1987). "The Einstein view of the Wolf-Rayet stars". The Astrophysical Journal. 320: 283. Bibcode:1987ApJ...320..283P. doi: 10.1086/165539 .
  8. ↑ Oliveira, Alexandre S.; Steiner, J. E.; Diaz, M. P. (April 2004). "The Multiple Spectroscopic and Photometric Periods of DI Crucis (WR 46)". Publications of the Astronomical Society of the Pacific. 116 (818): 311–325. doi: 10.1086/382899 . S2CID   10513657 . Retrieved 18 December 2021.
  9. ↑ Zhekov, S. A. (2012). "X-rays from colliding stellar winds: The case of close Wolf-Rayet+O binary systems". Monthly Notices of the Royal Astronomical Society. 422 (2): 1332–1342. arXiv: 1202.1386 . Bibcode:2012MNRAS.422.1332Z. doi:10.1111/j.1365-2966.2012.20706.x. S2CID   86867278.
  10. 1 2 Niemela, V. S.; Barba, R. H.; Shara, M. M. (1995). "The radial velocity variations of WR46 (WN3p)". Wolf-Rayet Stars: Binaries; Colliding Winds; Evolution. 163: 245. Bibcode:1995IAUS..163..245N. doi:10.1007/978-94-011-0205-6_56. ISBN   978-0-7923-3184-1.
  11. ↑ Steiner, J. E.; Diaz, M. P. (1998). "The V Sagittae Stars". Publications of the Astronomical Society of the Pacific. 110 (745): 276. Bibcode:1998PASP..110..276S. doi: 10.1086/316139 .
  12. ↑ Marchenko, Sergey V.; Arias, Julia; Barbá, Rodolfo; Balona, Luis; Moffat, Anthony F. J.; Niemela, Virpi S.; Shara, Michael M.; Sterken, Christiaan (2000). "The Puzzle of HD 104994 (WR 46)". The Astronomical Journal. 120 (4): 2101–2113. Bibcode:2000AJ....120.2101M. doi: 10.1086/301580 . ISSN   0004-6256.
  13. ↑ Marchenko, S. V.; Arias, J.; Barbá, R.; Balona, L.; Moffat, A. F. J.; Niemela, V. S.; Shara, M. M.; Sterken, C. (2000). "The Puzzle of HD 104994 (WR 46)". The Astronomical Journal. 120 (4): 2101. Bibcode:2000AJ....120.2101M. doi: 10.1086/301580 .
  14. ↑ Gosset, E.; De Becker, M.; Nazé, Y.; Carpano, S.; Rauw, G.; Antokhin, I. I.; Vreux, J. -M.; Pollock, A. M. T. (2011). "XMM-Newtonobservation of the enigmatic object WR 46". Astronomy & Astrophysics. 527: A66. Bibcode:2011A&A...527A..66G. doi: 10.1051/0004-6361/200912510 .
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