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Resolving Decades of Periodic Spirals from the Wolf–Rayet Dust Factory WR 112

Lau, Ryan M. and Hankins, Matthew J. and Han, Yinuo and Endo, Izumi and Moffat, Anthony F. J. and Ressler, Michael E. and Sakon, Itsuki and Sanchez-Bermudez, Joel and Soulain, Anthony and Stevens, Ian R. and Tuthill, Peter G. and Williams, Peredur M. (2020) Resolving Decades of Periodic Spirals from the Wolf–Rayet Dust Factory WR 112. Astrophysical Journal, 900 (2). Art. No. 190. ISSN 1538-4357.

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WR 112 is a dust-forming carbon-rich Wolf–Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR 112 therefore provides an opportunity to understand the dust formation process in colliding-wind WC binaries. In this work, we present a multi-epoch analysis of the circumstellar dust around WR 112 using seven high spatial resolution (FWHM ~ 0farcs3–0farcs4) N-band (λ ~ 12 μm) imaging observations spanning almost 20 yr and that includes images obtained from Subaru/COMICS in 2019 October. In contrast to previous interpretations of a face-on spiral morphology, we observe clear evidence of proper motion of the circumstellar dust around WR 112 consistent with a nearly edge-on spiral with a θ_s = 55° half-opening angle and a ~20 yr period. The revised near edge-on geometry of WR 112 reconciles previous observations of highly variable nonthermal radio emission that was inconsistent with a face-on geometry. We estimate a revised distance to WR 112 of d = 3.39_(-0.84)^(+0.89) kpc based on the observed dust expansion rate and a spectroscopically derived WC terminal wind velocity of v_∞ = 1230 ± 260 km s⁻¹. With the newly derived WR 112 parameters, we fit optically thin dust spectral energy distribution models and determine a dust production rate of Ṁ_d = 2.7_(-1.3)^(+1.0) x 10⁻⁶ M_⊙ yr⁻¹, which demonstrates that WR 112 is one of the most prolific dust-making WC systems known.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hankins, Matthew J.0000-0001-9315-8437
Ressler, Michael E.0000-0001-5644-8830
Sakon, Itsuki0000-0001-7641-5497
Sanchez-Bermudez, Joel0000-0002-9723-0421
Stevens, Ian R.0000-0001-7673-4340
Williams, Peredur M.0000-0002-8092-980X
Additional Information:© 2020. The American Astronomical Society. Received 2020 June 11; revised 2020 July 22; accepted 2020 July 22; published 2020 September 15. R.M.L. thanks D. Calderón, A. Lamberts, S.V. Marchenko, J.D. Monnier, T. Onaka, G. Rate, C..P. Russell, and R. Schödel for the valuable discussion on colliding winds in WC binaries and observations of WR 112. We thank the anonymous referee for the insightful comments and suggestions that have improved the clarity and quality of this work. R.M.L. also thanks T. Fujiyoshi and the Subaru Observatory staff for supporting our Subaru/COMICS observations of WR 112. R.M.L. acknowledges the Japan Aerospace Exploration Agency's International Top Young Fellowship. A.F.J.M. is grateful for financial aid from NSERC (Canada). Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 097.D-0707(A). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on observations obtained at the international Gemini Observatory, a program of NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). Based in part on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) and with the participation of ISAS and NASA. Based in part on observations in the service observing program of the WHT, operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This research made use of Astropy,15 a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018). Facilities: VLT(VISIR) - , Subaru(COMICS) - , Gemini South(T-ReCS) - , Keck I(LWS) - , Gemini North(OSCIR) - , ISO(SWS) - , WHT(ISIS). -
Funding AgencyGrant Number
Japan Aerospace Exploration Agency (JAXA)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Circumstellar dust ; WC stars ; Dust shells ; Dust nebulae ; Binary stars
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Circumstellar dust (236); WC stars (1793); Dust shells (414); Dust nebulae (413); Binary stars (154)
Record Number:CaltechAUTHORS:20200921-113043905
Persistent URL:
Official Citation:Ryan M. Lau et al 2020 ApJ 900 190
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105459
Deposited By: George Porter
Deposited On:24 Sep 2020 18:49
Last Modified:24 Sep 2020 18:49

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