The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆

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dc.contributor.authorClark, J S
dc.contributor.authorBartlett, E S
dc.contributor.authorBroos, P S
dc.contributor.authorTownsley, L K
dc.contributor.authorTaylor, W D
dc.contributor.authorWalborn, N R
dc.contributor.authorBird, A J
dc.contributor.authorSana, H
dc.contributor.authorde Mink, S E
dc.contributor.authorDufton, P L
dc.contributor.authorEvans, C J
dc.contributor.authorLanger, N
dc.contributor.authorMaíz Apellániz, J
dc.contributor.authorSchneider, F R N
dc.contributor.authorSoszyński, I
dc.date.accessioned2021-10-08T06:20:34Z
dc.date.available2021-10-08T06:20:34Z
dc.date.issued2015
dc.description.abstractContext: The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. Aims. One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity − in this study we aim to determine its physical nature and the cause of this behaviour. Methods. To accomplish this we performed a time-resolved analysis of optical, infrared and X-ray observations. Results. We found VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select He i lines − taken together these suggest an OeBe classification. The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that the accretor is a neutron star. Conclusions. VFTS 399 appears to be the first high-mass X-ray binary identified within 30 Dor, sharing many observational characteristics with classical Be X-ray binaries. Comparison of the current properties of VFTS 399 to binary-evolution models suggests a progenitor mass 25 M for the putative neutron star, which may host a magnetic field comparable in strength to those of magnetars. VFTS 399 is now the second member of the cohort of rapidly rotating “single” O-type stars in 30 Dor to show evidence of binary interaction resulting in spin-up, suggesting that this may be a viable evolutionary pathway for the formation of a subset of this stellar population.
dc.identifier.apacitationClark, J. S., Bartlett, E. S., Broos, P. S., Townsley, L. K., Taylor, W. D., Walborn, N. R., ... Soszyński, I. (2015). The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆. <i>Astronomy and Astrophysics</i>, 579(4), A131 - 177. http://hdl.handle.net/11427/34307en_ZA
dc.identifier.chicagocitationClark, J S, E S Bartlett, P S Broos, L K Townsley, W D Taylor, N R Walborn, A J Bird, et al "The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆." <i>Astronomy and Astrophysics</i> 579, 4. (2015): A131 - 177. http://hdl.handle.net/11427/34307en_ZA
dc.identifier.citationClark, J.S., Bartlett, E.S., Broos, P.S., Townsley, L.K., Taylor, W.D., Walborn, N.R., Bird, A.J. & Sana, H. et al. 2015. The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆. <i>Astronomy and Astrophysics.</i> 579(4):A131 - 177. http://hdl.handle.net/11427/34307en_ZA
dc.identifier.issn0004-6361
dc.identifier.issn1432-0746
dc.identifier.ris TY - Journal Article AU - Clark, J S AU - Bartlett, E S AU - Broos, P S AU - Townsley, L K AU - Taylor, W D AU - Walborn, N R AU - Bird, A J AU - Sana, H AU - de Mink, S E AU - Dufton, P L AU - Evans, C J AU - Langer, N AU - Maíz Apellániz, J AU - Schneider, F R N AU - Soszyński, I AB - Context: The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. Aims. One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity − in this study we aim to determine its physical nature and the cause of this behaviour. Methods. To accomplish this we performed a time-resolved analysis of optical, infrared and X-ray observations. Results. We found VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select He i lines − taken together these suggest an OeBe classification. The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that the accretor is a neutron star. Conclusions. VFTS 399 appears to be the first high-mass X-ray binary identified within 30 Dor, sharing many observational characteristics with classical Be X-ray binaries. Comparison of the current properties of VFTS 399 to binary-evolution models suggests a progenitor mass 25 M for the putative neutron star, which may host a magnetic field comparable in strength to those of magnetars. VFTS 399 is now the second member of the cohort of rapidly rotating “single” O-type stars in 30 Dor to show evidence of binary interaction resulting in spin-up, suggesting that this may be a viable evolutionary pathway for the formation of a subset of this stellar population. DA - 2015 DB - OpenUCT DP - University of Cape Town IS - 4 J1 - Astronomy and Astrophysics LK - https://open.uct.ac.za PY - 2015 SM - 0004-6361 SM - 1432-0746 T1 - The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆ TI - The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆ UR - http://hdl.handle.net/11427/34307 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34307
dc.identifier.vancouvercitationClark JS, Bartlett ES, Broos PS, Townsley LK, Taylor WD, Walborn NR, et al. The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆. Astronomy and Astrophysics. 2015;579(4):A131 - 177. http://hdl.handle.net/11427/34307.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Astronomy
dc.publisher.facultyFaculty of Science
dc.sourceAstronomy and Astrophysics
dc.source.journalissue4
dc.source.journalvolume579
dc.source.paginationA131 - 177
dc.source.urihttps://dx.doi.org/10.1051/0004-6361/201424427
dc.subject.othernature
dc.subject.otherpopulation
dc.subject.othercohorte
dc.subject.otherprospection
dc.subject.otherrégion
dc.subject.otherclassification
dc.subject.otherAssomption
dc.subject.otherpartage
dc.subject.otheranalyse comparative
dc.subject.othermesse
dc.subject.otherpreuve
dc.titleThe VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399⋆
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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