Variability of Young Massive Stars in the Galactic Super Star Cluster Westerlund 1

Abstract

This paper presents the first optical variability study of the Westerlund 1 super star cluster in search of massive eclipsing binary systems. A total of 129 new variable stars have been identified, including the discovery of 4 eclipsing binaries that are cluster members, 1 additional candidate, 8 field binaries, 19 field delta Scuti stars, 3 field W UMa eclipsing binaries, 13 other periodic variables and 81 long period or non-periodic variables. These include the known luminous blue variable, the B[e] star, 11 Wolf-Rayet stars, several supergiants, and other reddened stars that are likely members of Westerlund 1. The bright X-ray source corresponding to the Wolf-Rayet star WR77o (B) is found to be a 3.51 day eclipsing binary. The discovery of a reddened detached eclipsing binary system implies the first identification of main-sequence stars in Westerlund 1.

28 pages, 9 figures, 3 tables; accepted for publication in The Astronomical Journal. Full-resolution version and color image of the cluster are available at http://www.dtm.ciw.edu/bonanos/Westerlund1

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Cited by in corpus (15)

• Intermediate to low-mass stellar content of Westerlund 1
• Comparative performance of selected variability detection techniques in photometric time series
• A VLT/FLAMES survey for massive binaries in Westerlund 1. IV. Wd1-5 - binary product and a pre-supernova companion for the magnetar CXOU J1647-45?
• Extinction law in the range 0.4-4.8 $\mu$m and the 8620 $\mathring{A}$ DIB towards the stellar cluster Westerlund 1
• Towards an Accurate Determination of Parameters for Very Massive Stars: the Eclipsing Binary LMC-SC1-105
• The Age of Westerlund 1 Revisited
• Low Metallicity Indicates that the Hypervelocity Star HE 0437-5439 was Ejected from the LMC
• Hierarchical formation of Westerlund 1: a collapsing cluster with no primordial mass segregation?
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VIII. Binary Systems and Orbital Parameters
• ALMA observations of the supergiant B[e] star Wd1-9
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VI. Properties of X-ray bright massive cluster members
• Distance and age of the massive stellar cluster Westerlund 1. II. The eclipsing binary W36
• EWOCS-IV: 1Ms ACIS Chandra observation of the supergiant B[e] star Wd1-9
• Westerlund 1 as a Template for Massive Star Evolution
• EWOCS-V: Is Wd1-72 a recent post-interaction WR+O binary?