The binary nature of the Galactic Centre X-ray source CXOGC J174536.1-285638

Abstract

X-ray and near-IR surveys of the central 2x0.8 degrees of the Galactic Centre have revealed a population of X-ray bright massive stars. However, the nature of the emission, originating in a wind collision zone or via accretion onto a compact object, is uncertain. In order to address this we investigated the nature of the luminous X-ray source CXOGC J174536.1-285638. An analysis of the near-IR spectrum with a non-LTE model atmosphere code demonstrated that it was an highly luminous WN9h star, for which comparison to evolutionary tracks suggests an age of 2-2.5Myr and an initial mass of ~110Msun. The X-ray properties of CXOGC J174536.1-285638 resemble those of 3 of the WN9h stars within the Arches cluster and in turn other very massive WNLh colliding wind binaries. Simple analytical arguments demonstrate consistency between the X-ray emission and a putative WN9h+mid O V-III binary. However, we may not exclude a high mass X-ray binary interpretation, which, if correct, would provide a unique insight into the (post-SN) evolution of extremely massive stars. Irrespective of the nature of the secondary, CXOGC J174536.1-285638 adds to the growing list of known and candidate WNLh binaries. Of the subset of WNLh stars subject to a radial velocity survey, we find a lower limit to the binary fraction of ~45%; of interest for studies of massive stellar formation, given that they currently possess the highest dynamically determined masses of any type of star. [ABRIDGED]

9 pages, 5 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (27)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The UKIRT Wide Field Camera ZYJHK Photometric System: Calibration from 2MASS
• The Galactic WN stars: Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation
• UBVJHK synthetic photometry of Galactic O stars
• Rotational mixing in massive binaries: detached short-period systems
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• The most massive stars in the Arches cluster
• A Catalog of X-ray Point Sources from Two Megaseconds of Chandra Observations of the Galactic Center
• A Spectroscopic Survey of WNL Stars in the LMC: General Properties and Binary Status
• The Arches Cluster Mass Function
• The Interplay between Star Formation and the Nuclear Environment of our Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet Clusters
• VLT/UVES spectroscopy of Wray 977, the hypergiant companion to the X-ray pulsar GX301-2
• The very massive binary NGC3603-A1
• A third red supergiant rich cluster in the Scutum-Crux Arm
• A Chandra Catalog of X-ray Sources in the Central 150 pc of the Galaxy
• Magnetic field measurements of O stars with FORS1 at the VLT
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• A VLT/FLAMES survey for massive binaries in Westerlund 1: I. first observations of luminous evolved stars
• A first orbital solution for the very massive 30 Dor main-sequence WN6h+O binary R145
• HD148937: a multiwavelength study of the third Galactic member of the Of?p class
• Chandra monitoring of the very massive binary WR20a and the young massive cluster Westerlund2
• Two extremely luminous WN stars in the Galactic center with circumstellar emission from dust and gas
• The very massive X-ray bright binary system Wack 2134 (= WR 21a)
• Spectral classification of the mass donors in the high-mass X-ray binaries EXO 1722-363 and OAO 1657-415
• Towards an understanding of the Of?p star HD191612: Phase-resolved multiwavelength observations
• Identification of the Infrared Counterpart to a Newly Discovered X-ray Source in the Galactic Center
• XMM-Newton observations of Zeta Orionis (O9.7 Ib): A Collisional Ionization Equilibrium model

Cited by in corpus (12)

• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• Near-infrared counterparts to Chandra X-ray sources toward the Galactic Center. II. Discovery of Wolf-Rayet stars and O supergiants
• A serendipitous survey for variability amongst the massive stellar population of Westerlund 1
• A VLT/FLAMES survey for massive binaries in Westerlund 1: I. first observations of luminous evolved stars
• The eclipsing, double-lined, Of supergiant binary Cyg OB2-B17
• Constraining the population of isolated massive stars within the Central Molecular Zone
• A population of compact radio variables and transients in the radio bright zone at the Galactic center observed with the Jansky Very Large Array
• The VLT-FLAMES Tarantula survey XX. The nature of the X-ray bright emission line star VFTS 399
• The Arches cluster revisited: IV. Observational constraints on the binary properties of very massive stars
• Near-infrared counterparts of Chandra X-ray sources toward the Galactic Center
• On the Dynamical Evolution of the Arches Cluster
• Chandra X-ray Measurement of Heavy Element Abundances of Wolf-Rayet Stars in the Galactic Center