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A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf–Rayet stars

Shara, Michael M. and Howell, Steve B. and Furlan, Elise and Gnilka, Crystal L. and Moffat, Anthony F. J. and Scott, Nicholas J. and Zurek, David (2022) A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf–Rayet stars. Monthly Notices of the Royal Astronomical Society, 509 (2). pp. 2897-2907. ISSN 0035-8711. doi:10.1093/mnras/stab2666.

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Gravitationally bound companions to stars enable determinations of their masses, and offer clues to their formation, evolution, and dynamical histories. So motivated, we have carried out a speckle imaging survey of eight of the nearest and brightest Wolf–Rayet (WR) stars to directly measure the frequency of their resolvable companions, and to search for much fainter companions than hitherto possible. We found one new, close companion to each of WR 113, WR 115, and WR 120 in the separation range ∼0.2–1.2 arcsec². Our results provide more evidence that similar-brightness, close companions to WR stars are common. More remarkably, they also demonstrate that the predicted, but much fainter and thus elusive companions to WR stars are now within reach of modern speckle cameras on 8-m class telescopes by finding the first example. The new companion to WR 113 is just 1.16 arcsec distant from it, and is ∼8 mag fainter than the WR star. The empirical probability of a chance line of sight of the faint companion at the position of WR 113 is <0.5 per cent, though we cannot yet prove or disprove if the two stars are gravitationally bound. If these three new detections are physical companions we suggest, based on their narrowband magnitudes, colours, reddenings, and GAIA distances that the companions to WR113, WR 115, and WR 120 are an F-type dwarf, an early B-type dwarf, and a WNE-type WR star, respectively.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Shara, Michael M.0000-0003-0155-2539
Howell, Steve B.0000-0002-2532-2853
Furlan, Elise0000-0001-9800-6248
Gnilka, Crystal L.0000-0003-2519-6161
Moffat, Anthony F. J.0000-0002-4333-9755
Scott, Nicholas J.0000-0003-1038-9702
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 September 12. Received 2021 September 5; in original form 2021 July 5. Published: 21 September 2021. The data presented in this paper are based on observations obtained at the international Gemini Observatory, a program of NSF’s 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). This work was enabled by observations made from the Gemini North telescope, located within the Maunakea Science Reserve and adjacent to the summit of Maunakea. We are grateful for the privilege of observing the Universe from a place that is unique in both its astronomical quality and its cultural significance. Observations in the paper made use of the High-Resolution Imaging instrument ‘Alopeke, which was funded by the NASA Exoplanet Exploration Program, built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley, and mounted on the Gemini-North telescope of the international Gemini Observatory. AFJM is grateful to NSERC (Canada) for financial aid. We thank the referee, Paul Crowther, for a thorough and thoughtful review which improved the paper, and for the WR star distances in Table 1. MMS thanks Mordecai Mac Low for discussions about binary star formation. We thank the Canadian Gemini Time Allocation Committee for excellent feedback and support, and their allocation of telescope time. The observations were obtained under Gemini proposal GN-2020A-Q-110. Data Availability Statement: The data underlying this article will be shared on reasonable request to the corresponding author.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:techniques: high angular resolution – binaries: close – stars: Wolf–Rayet
Issue or Number:2
Record Number:CaltechAUTHORS:20220118-112249000
Persistent URL:
Official Citation:Michael M Shara, Steve B Howell, Elise Furlan, Crystal L Gnilka, Anthony F J Moffat, Nicholas J Scott, David Zurek, A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf–Rayet stars, Monthly Notices of the Royal Astronomical Society, Volume 509, Issue 2, January 2022, Pages 2897–2907,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112944
Deposited By: Tony Diaz
Deposited On:18 Jan 2022 22:54
Last Modified:18 Jan 2022 22:54

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