WR 46: Difference between revisions
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==Variability== |
==Variability== |
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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 [[Photometry (astronomy)|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.<ref name=zhekov>{{cite doi|10.1111/j.1365-2966.2012.20706.x}}</ref> Theories that are now discounted include WR 46 being a [[Super soft X-ray source]]<ref name=niemela/> or a V Sagittae star,<ref name=steiner>{{cite doi|10.1086/316139}}</ref> |
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 [[Photometry (astronomy)|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.<ref name=zhekov>{{cite doi|10.1111/j.1365-2966.2012.20706.x}}</ref> Theories that are now discounted include WR 46 being a [[Super soft X-ray source]]<ref name=niemela/> or a V Sagittae star,<ref name=steiner>{{cite doi|10.1086/316139}}</ref> |
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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<ref name="marchenko2000>{{cite journal|last1=Marchenko|first1=Sergey V.|last2=Arias|first2=Julia|last3=Barbá|first3=Rodolfo|last4=Balona|first4=Luis|last5=Moffat|first5=Anthony F. J.|last6=Niemela|first6=Virpi S.|last7=Shara|first7=Michael M.|last8=Sterken|first8=Christiaan|title=The Puzzle of HD 104994 (WR 46)|journal=The Astronomical Journal|volume=120|issue=4|year=2000|pages=2101–2113|issn=00046256|doi=10.1086/301580}}</ref> |
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==Binary star== |
==Binary star== |
Revision as of 12:59, 14 August 2015
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: -5.44[1] mas/yr Dec.: 1.84[1] mas/yr |
Parallax (π) | 2.45 mas[1] |
Distance | 4,070[6] pc |
Absolute magnitude (MV) | −3.50[3] |
Details | |
Mass | 25[3] M☉ |
Radius | 2.11[3] R☉ |
Luminosity | 630,000[3] L☉ |
Temperature | 112,000[3] K |
Other designations | |
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 OB4 Cru, and is around 4,000 parsecs or 13,000 light years from the Solar System.
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 600,000 times the solar luminosity (L☉), the mass around 25 times that of the Sun (M☉) and a radius of 2.9 times the solar radius (R☉). The terminal velocity of the stellar wind reaches 2450 km/s with a total mass loss rate of 4 × 10−6 M☉ 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
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.[8] Theories that are now discounted include WR 46 being a Super soft X-ray source[9] or a V Sagittae star,[10]
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[11]
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[9] and 0.329 days.[12] Most recent research refutes the idea of a companion, instead favoring the single WN star theory.[13]
References
- ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ^ a b c Reed, B. Cameron (2003). "Catalog of Galactic OB Stars". The Astronomical Journal. 125 (5): 2531–2533. doi:10.1086/374771. ISSN 0004-6256.
- ^ a b c d e f Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1051/0004-6361:20065052, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
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instead. - ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1088/0004-637X/735/1/13, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
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instead. - ^ 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. doi:10.1051/0004-6361:20041213. ISSN 0004-6361.
- ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/S1387-6473(00)00112-3, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
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instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1086/165539, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
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instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1365-2966.2012.20706.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
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instead. - ^ a b Bibcode:1995IAUS..163..245N
- ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1086/316139, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1086/316139
instead. - ^ 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. doi:10.1086/301580. ISSN 0004-6256.
- ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1086/301580, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1086/301580
instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1051/0004-6361/200912510
, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1051/0004-6361/200912510
instead.
External links
This article is based on the Spanish version es.wikipedia.org/wiki/DI Crucis