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.

arXiv comment28 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

References in corpus (20)

• The USNO-B Catalog
• A method for optimal image subtraction
• Homogeneous Photometry for Star Clusters and Resolved Galaxies. II. Photometric Standard Stars
• On the massive stellar population of the Super Star Cluster Westerlund 1
• The Carnegie Supernova Project: The Low-Redshift Survey
• High-Redshift Gamma-Ray Bursts from Population III Progenitors
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• WR 20a is an Eclipsing Binary: Accurate Determination of Parameters for an Extremely Massive Wolf-Rayet System
• The First DIRECT Distance Determination to a Detached Eclipsing Binary in M33
• Binaries Like to be Twins: Implications for Doubly Degenerate Binaries, the Supernova Ia Rate and Other Interacting Binaries
• WR20a: a massive cornerstone binary system comprising two extreme early-type stars
• HAT Variability Survey in the High Stellar Density "Kepler Field" with Millimagnitude Image Subtraction Photometry
• Diffuse, Non-Thermal X-ray Emission from the Galactic Star Cluster Westerlund 1
• Orbits of Four Very Massive Binaries in the R136 Cluster
• New Galactic Wolf-Rayet stars, and candidates. An annex to The VIIth Catalogue of Galactic Wolf-Rayet Stars
• A Rich Population of X-ray Emitting Wolf-Rayet Stars in the Galactic Starburst Cluster Westerlund 1
• A hidden population of Wolf-Rayet stars in the massive galactic cluster Westerlund 1
• Excitation of g modes in Wolf-Rayet stars by a deep opacity bump
• The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary
• Re-analysis of VLT Data for M83 with Image Subtraction -- Nine-fold Increase in Number of Cepheids

Cited by in corpus (35)

• Toward Understanding Massive Star Formation
• Intermediate to low-mass stellar content of Westerlund 1
• The population of OB supergiants in the starburst cluster Westerlund 1
• Comparative performance of selected variability detection techniques in photometric time series
• The Starburst Cluster Westerlund 1: The Initial Mass Function and Mass Segregation
• 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?
• A serendipitous survey for variability amongst the massive stellar population of Westerlund 1
• Extinction law in the range 0.4-4.8 $\mu$m and the 8620 $\mathring{A}$ DIB towards the stellar cluster Westerlund 1
• A VLT/FLAMES survey for massive binaries in Westerlund 1: I. first observations of luminous evolved stars
• Spectroscopic monitoring of the luminous blue variable Westerlund1-243 from 2002 to 2009
• Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1
• Towards an Accurate Determination of Parameters for Very Massive Stars: the Eclipsing Binary LMC-SC1-105
• The circumstellar environment and evolutionary state of the supergiant B[e] star Wd1-9
• The Age of Westerlund 1 Revisited
• Massive stars in the Cl 1813-178 Cluster. An episode of massive star formation in the W33 complex
• The Optical/Near-Infrared Extinction Law In Highly Reddened Regions
• A VLT/FLAMES survey for massive binaries in Westerlund 1. III. The WC9d binary W239 and implications for massive stellar evolution
• Fundamental Parameters of four Massive Eclipsing Binaries in Westerlund 1
• Low Metallicity Indicates that the Hypervelocity Star HE 0437-5439 was Ejected from the LMC
• The Fundamental Parameters of Four Massive Eclipsing Binaries in Westerlund 1
• An ALMA 3mm continuum census of Westerlund 1
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VII. Cluster census
• 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 V. the X-ray selected blue stragglers Wd1-27 and -30a
• A Radio Census of the Massive Stellar Cluster Westerlund 1
• Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1
• 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
• The HST Key Project galaxies NGC 1326A, NGC 1425 and NGC 4548: New variable stars and massive star population
• EWOCS-IV: 1Ms ACIS Chandra observation of the supergiant B[e] star Wd1-9
• Westerlund 1 as a Template for Massive Star Evolution
• Fundamental Parameters of 4 Massive Eclipsing Binaries in Westerlund 1
• EWOCS-V: Is Wd1-72 a recent post-interaction WR+O binary?