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Stagnant Shells in the Vicinity of the Dusty Wolf–Rayet–OB Binary WR 112

Lau, R. M. and Hankins, M. J. and Schödel, R. and Sanchez-Bermudez, J. and Moffat, A. F. J. and Ressler, M. E. (2017) Stagnant Shells in the Vicinity of the Dusty Wolf–Rayet–OB Binary WR 112. Astrophysical Journal Letters, 835 (2). Art. No. L31. ISSN 2041-8205.

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We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf–Rayet (WC)–OB binary system WR 112 taken by the recently upgraded VLT spectrometer and imager for the mid-infrared (VISIR) with the PAH1, Ne II_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments and broken shells. Dust temperatures and masses are derived for each of the identified filamentary structures, which exhibit temperatures ranging from 179^(+8)_(-6)K at the exterior W2 filament to 355^(+37)_(-25)K in the central 3''. The total dust mass summed over the features is 2.6 ± 0.4 × 10^(−5) M⊙. A multi-epoch analysis of mid-IR photometry of WR 112 over the past ~20 years reveals no significant variability in the observed dust temperature and mass. The morphology of the mid-IR dust emission from WR 112 also exhibits no significant expansion from imaging data taken in 2001, 2007, and 2016, which disputes the current interpretation of the nebula as a high expansion velocity (~1200 km s−1) "pinwheel"-shaped outflow driven by the central WC–OB colliding-wind binary. An upper limit of ≾120 km s^(−1) is derived for the expansion velocity assuming a distance of 4.15 kpc. The upper limit on the average total mass-loss rate from the central 3'' of WR 112 is estimated to be ≾8 × 10^(−6) M⊙ year^(−1). We leave its true nature as an open question, but propose that the WR 112 nebula may have formed in the outflow during a previous red or yellow supergiant phase of the central Wolf–Rayet star.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hankins, M. J.0000-0001-9315-8437
Additional Information:© 2017 The American Astronomical Society. Received 2016 October 8; revised 2016 December 14; accepted 2016 December 14; published 2017 January 30. This work is based on observations made with the VISIR instrument on the ESO VLT telescope (program ID. 097.D-0707A) and observations obtained at the Gemini Observatory (P.ID: GS-2007A-Q-38), 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), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). This work was partially carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. M.J.H. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant No. DGE-1144153. J.S.B. acknowledges that this work was partly supported by OPTICON, which is sponsored by the European Commission's FP7 Capacities programme (grant No. 312430). A.F.J.M. is grateful for financial aid to NSERC (Canada) and FQRNT (Quebec). R.S. acknowledges funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement No. [614922]. R.L. would like to thank Sergey Marchenko for valuable feedback and comments, and Jim De Buizer and James Radomski for the helpful insight on T-ReCS imaging data. R.L. also thanks Astrid Lamberts for the enlightening conversations on colliding-wind binaries. Finally, we thank the anonymous referee for the insightful suggestions and comments.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144153
European Research Council (ERC)312430
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT)UNSPECIFIED
European Research Council (ERC)614922
Subject Keywords:infrared: stars – stars: individual (WR 112) – stars: winds, outflows – stars: Wolf–Rayet
Issue or Number:2
Record Number:CaltechAUTHORS:20170131-100110091
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Official Citation:R. M. Lau et al 2017 ApJL 835 L31
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73867
Deposited By: Tony Diaz
Deposited On:31 Jan 2017 18:12
Last Modified:09 Mar 2020 13:18

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