The Arches cluster revisited: II. A massive eclipsing spectroscopic binary in the Arches cluster

Lohr, M. E.; Clark, J. S.; Najarro, F.; Patrick, L. R.; Crowther, P. A. and Evans, C. J. (2018). The Arches cluster revisited: II. A massive eclipsing spectroscopic binary in the Arches cluster. Astronomy & Astrophysics, 617, article no. A66.

DOI: https://doi.org/10.1051/0004-6361/201832670

Abstract

We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity; in combination with new KMOS and archival SINFONI spectra, its primary component is found to undergo radial velocity variation with a period of 10.483+/-0.002 d and an amplitude of ~350 km/s^-1. A secondary radial velocity curve is also marginally detectable. We reanalyse archival NAOS-CONICA photometric survey data in combination with our radial velocity results to confirm this object as an eclipsing SB2 system, and the first binary identified in the Arches. We model it as consisting of an 82+/-12 M_⊙ WN8-9h primary and a 60+/-8 M_⊙ O5-6 Ia⁺ secondary, and as having a slightly eccentric orbit, implying an evolutionary stage prior to strong binary interaction. As one of four X-ray bright Arches sources previously proposed as colliding-wind massive binaries, it may be only the first of several binaries to be discovered in this cluster, presenting potential challenges to recent models for the Arches' age and composition. It also appears to be one of the most massive binaries detected to date; the primary's calculated initial mass of >~120 M_⊙ would arguably make this the most massive binary known in the Galaxy.

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About

• Item ORO ID
• 55327
• Item Type
• Journal Item
• ISSN
• 1432-0746
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Consolidated Grant - Astronomy Observation and Astronomy Theory (AO & AT 2016)	ST/P000584/1	STFC (Science & Technology Facilities Council)
  Not Set	FJCI-2014-23001	Spanish Government Ministerio de Economia y Competitivad
  Not Set	AYA2015-68012-C2-2-P	Spanish Government Ministerio de Economia y Competitivad

• Keywords
• stars; massive stars; Wolf-Rayet stars; close binaries; eclipsing binaries; spectroscopic binaries
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• Astronomy
• Copyright Holders
• © 2018 ESO
• Related URLs
• • http://oro.open.ac.uk/55330/(Publication)
  • https://arxiv.org/abs/1804.05607(Other)
• Depositing User
• Marcus Lohr