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Investigating the origin of the spectral line profiles of the Hot Wolf–Rayet Star WR 2

Chené, A.-N. and St-Louis, N. and Moffat, A. F. J. and Schnurr, O. and Crowther, P. A. and Wade, G. A. and Richardson, N. D. and Baranec, C. and Ziegler, C. A. and Law, N. M. and Riddle, R. and Rate, G. A. and Artigau, É. and Alecian, E. (2019) Investigating the origin of the spectral line profiles of the Hot Wolf–Rayet Star WR 2. Monthly Notices of the Royal Astronomical Society, 484 (4). pp. 5834-5844. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20190415-154511959

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Abstract

The hot WN star WR 2 (HD 6327) has been claimed to have many singular characteristics. To explain its unusually rounded and relatively weak emission line profiles, it has been proposed that WR 2 is rotating close to break-up with a magnetically confined wind. Alternatively, the line profiles could be explained by the dilution of WR 2’s spectrum by that of a companion. In this paper, we present a study of WR 2 using near-infrared AO imaging and optical spectroscopy and polarimetry. Our spectra reveal the presence of weak photospheric absorption lines from a B 2.5–4V companion, which however contributes only 5–10 per cent to the total light, suggesting that the companion is a background object. Therefore, its flux cannot be causing any significant dilution of the WR star’s emission lines. The absence of intrinsic linear continuum polarization from WR 2 does not support the proposed fast rotation. Our Stokes V spectrum was not of sufficient quality to test the presence of a moderately strong organized magnetic field but our new modelling indicates that to confine the wind the putative magnetic field must be significantly stronger than was previously suggested sufficiently strong as to make its presence implausible.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stz411DOIArticle
ORCID:
AuthorORCID
Chené, A.-N.0000-0002-1115-6559
St-Louis, N.0000-0003-3890-3400
Richardson, N. D.0000-0002-2806-9339
Baranec, C.0000-0002-1917-9157
Law, N. M.0000-0001-9380-6457
Riddle, R.0000-0002-0387-370X
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 January 30. Received 2019 January 28; in original form 2018 October 6. Published: 11 February 2019. ANC gratefully acknowledges support Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). AFJM, NSL, and GAW acknowledge financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada. NDR gratefully acknowledges his Centre de Recherche en Astrophysique du Québec (CRAQ) Fellowship. ANC and GAW finally gratefully thank A. de la Chevrotière and S. P. Owocki for discussions and input that led to the significant improvement of this manuscript. NDR acknowledges postdoctoral support by the University of Toledo and by the Helen Luedtke Brooks Endowed Professorship. The Robo-AO system was developed by collaborating partner institutions, the California Institute of Technology and the Inter-University Centre for Astronomy and Astrophysics, and with the support of the National Science Foundation under Grant Nos. AST-0906060, AST-0960343, and AST-1207891, the Mt. Cuba Astronomical Foundation and by a gift from Samuel Oschin. Ongoing science operation support of Robo-AO is provided by the California Institute of Technology and the University of Hawai‘i. C.B. acknowledges support from the Alfred P. Sloan Foundation. CZ is supported by a Dunlap Fellowship at the Dunlap Institute for Astronomy & Astrophysics, funded through an endowment established by the Dunlap family and the University of Toronto. Based on observations obtained at the Gemini Observatory, processed using the Gemini IRAF package. The program ID are GN-2012B-Q-115 and GN-2014B-Q-109. Based on observations obtained at the Canada–France−Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of Francethe University of Hawaii. Also based on obsrvations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministèrio da Ciència, Tecnologia e Inovação (Brazil), and Ministèrio de Ciència, Tecnología e Innovación Productiva (Argentina).
Funders:
Funding AgencyGrant Number
Gemini ObservatoryUNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Centre de Recherche en Astrophysique du Québec (CRAQ)UNSPECIFIED
University of ToledoUNSPECIFIED
Helen Luedtke Brooks Endowed ProfessorshipUNSPECIFIED
NSFAST-0906060
NSFAST-0960343
NSFAST-1207891
Mt. Cuba Astronomical FoundationUNSPECIFIED
Samuel OschinUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
University of TorontoUNSPECIFIED
NSFUNSPECIFIED
National Research Council of CanadaUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Australian Research CouncilUNSPECIFIED
Ministèrio da Ciència, Tecnologia e Inovação (MCTI)UNSPECIFIED
Ministerio de Ciencia, Tecnología e Innovación ProductivaUNSPECIFIED
Subject Keywords:stars: individual: WR 2 – stars: magnetic fields – stars: rotation – stars: winds, outflows – stars: Wolf–Rayet
Record Number:CaltechAUTHORS:20190415-154511959
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190415-154511959
Official Citation:A-N Chené, N St-Louis, A F J Moffat, O Schnurr, P A Crowther, G A Wade, N D Richardson, C Baranec, C A Ziegler, N M Law, R Riddle, G A Rate, É Artigau, E Alecian, Investigating the origin of the spectral line profiles of the Hot Wolf–Rayet Star WR 2, Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 4, April 2019, Pages 5834–5844, https://doi.org/10.1093/mnras/stz411
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94722
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Apr 2019 20:12
Last Modified:16 Apr 2019 20:12

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