First Visual Orbit for the Prototypical Colliding-wind Binary WR 140
ten Brummelaar, T
Astrophysical Journal Letters
American Astronomical Society / IOP Publishing
© 2011. The American Astronomical Society. All rights reserved.
Wolf-Rayet (WR) stars represent one of the final stages of massive stellar evolution. Relatively little is known about this short-lived phase and we currently lack reliable mass, distance, and binarity determinations for a representative sample. Here we report the first visual orbit for WR 140 (= HD193793), a WC7+O5 binary system known for its periodic dust production episodes triggered by intense colliding winds near periastron passage. The Infrared-Optical Telescope Array and Center for High Angular Resolution Astronomy interferometers resolved the pair of stars in each year from 2003 to 2009, covering most of the highly eccentric, 7.9 year orbit. Combining our results with the recently improved double-line spectroscopic orbit of Fahed et al., we find the WR 140 system is located at a distance of 1.67 ± 0.03 kpc, composed of a WR star with M WR = 14.9 ± 0.5 M ☉ and an O star with M O = 35.9 ± 1.3 M ☉. Our precision orbit yields key parameters with uncertainties ~6× smaller than previous work and paves the way for detailed modeling of the system. Our newly measured flux ratios at the near-infrared H and Ks bands allow a spectral energy distribution decomposition and analysis of the component evolutionary states.
We have appreciated discussions with Tony Moffat, Peter Tuthill, Debra Wallace, Bill Danchi, Sean Dougherty, and Remi Fahed during the (long) course of this work. We thank SAO, U. Mass, NSF AST-0138303, NSF AST-0352723, and NASA NNG05G1180G for supporting IOTA development and operations. We also acknowledge funding from GSU, the Keck Foundation, and NSF AST-0908253 for the CHARA Array. IONIC-3 was developed by LAOG (now IPAG) and LETI in the context of the IONIC collaboration (LAOG, IMEP, LETI), funded by the CNRS and CNES (France). Lastly we thank NSF AST-0807577 for support of University of Michigan researchers in this work. E.P. received funding from a Michelson Postdoctoral Fellowship and a Scottish Universities Physics Alliance (SUPA) advanced fellowship. P.M.W. is grateful to the Institute for Astronomy for hospitality and continued access to the facilities of the Royal Observatory, Edinburgh. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and NASA's Astrophysics Data System (ADS) Bibliographic Services.
This is the final version of the article. Available from American Astronomical Society via the DOI in this record.
Vol. 742 (1), article L1