Discovery of X-ray Emission from the Wolf-Rayet star WR142 of oxygen subtype

Abstract

We report the discovery of weak yet hard X-ray emission from the Wolf-Rayet (WR) star WR142 with the XMM-Newton X-ray telescope. Being of spectral subtype WO2, WR142 is a massive star in a very advanced evolutionary stage, short before its explosion as a supernova or gamma-ray burst. This is the first detection of X-ray emission from a WO-type star. We rule out any serendipitous X-ray sources within approx 1" of WR142. WR142 has an X-ray luminosity of L_X=7\times10^{30} erg/s, which constitutes only $\lsim 10^{-8}$ of its bolometric luminosity. The hard X-ray spectrum suggests a plasma temperature of about 100 MK. Commonly, X-ray emission from stellar winds is attributed to embedded shocks due to the intrinsic instability of the radiation driving. From qualitative considerations we conclude that this mechanism cannot account for the hardness of the observed radiation. There are no hints for a binary companion. Therefore the only remaining, albeit speculative explanation must refer to magnetic activity. Possibly related, WR142 seems to rotate extremely fast, as indicated by the unusually round profiles of its optical emission lines. Our detection implies that the wind of WR142 must be relatively transparent to X-rays, which can be due to strong wind ionization, wind clumping, or non-spherical geometry from rapid rotation.

arXiv commentaccepted ApJL

References in corpus (23)

• The USNO-B Catalog
• The Galactic WN stars: Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation
• Stellar evolution with rotation XIII: Predicted GRB rates at various Z
• An XMM-Newton view of the young open cluster NGC 6231 -- II. The OB star population
• Hydrodynamic model atmospheres for WR stars: Self-consistent modeling of a WC star wind
• High resolution X-ray spectroscopy of bright O type stars
• Evolution of X-ray emission from young massive star clusters
• X-ray line emission from a fragmented stellar wind
• An Extensive Collection of Stellar Wind X-ray Source Region Emission Line Parameters,Temperatures, Velocities, and Their Radial Distributions as Obtained from Chandra Observations of 17 OB Stars
• The Conspicuous Absence of X-ray Emission from Carbon-Enriched Wolf-Rayet Stars
• X-ray Emission Line Profile Modeling of O stars: Fitting a Spherically-Symmetric Analytic Wind-Shock Model to the Chandra Spectrum of zeta Puppis
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• Hot Gas in the Circumstellar Bubble S308
• Spectroscopic binaries with components of similar mass
• An X-ray Survey of Wolf-Rayet Stars in the Magellanic Clouds. I. The Chandra ACIS Dataset
• XMM-Newton Detection of Hard X-ray Emission in the Nitrogen-Type Wolf-Rayet Star WR110
• A new paradigm for the X-ray emission of O stars from XMM-Newton observations of the O9.7 supergiant zeta Orionis
• XMM-Newton and VLA Observations of the Variable Wolf-Rayet Star EZ CMa: Evidence for a Close Companion?
• Profile Shapes for Optically Thick X-ray Emission Lines from Stellar Winds
• Colliding Stellar Wind Models with Nonequilibrium Ionization: X-rays from WR 147
• Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra
• X-ray Emission from Wind Blown Bubbles. III. ASCA SIS Observations of NGC6888
• An X-ray Survey of Wolf-Rayet Stars in the Magellanic Clouds. II. The ROSAT PSPC and HRI Datasets

Cited by in corpus (24)

• X-Ray Spectroscopy of Stars
• The Galactic WC stars: Stellar parameters from spectral analyses indicate a new evolutionary sequence
• The Galactic WC and WO stars: The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors
• Near-infrared counterparts to Chandra X-ray sources toward the Galactic Center. II. Discovery of Wolf-Rayet stars and O supergiants
• Magnetic fields in massive stars, their winds, and their nebulae
• XMM-Newton (X-Ray Mulit-Mirror Mission) Observatory
• X-rays observations of a super-Chandrasekhar object reveal an ONeMg and a CO white dwarf merger product embedded in a putative SN Iax remnant
• The Massive Star-Forming Regions Omnibus X-Ray Catalog, Second Installment
• Observational properties of massive black hole binary progenitors
• The Massive Star-Forming Regions Omnibus X-Ray Catalog, Third Installment
• Searching for a magnetic field in Wolf-Rayet stars using FORS2 spectropolarimetry
• Diagnostic of the unstable envelopes of Wolf-Rayet stars
• XMM-Newton Observations Reveal Very High X-ray Luminosity from the Carbon-rich Wolf-Rayet Star WR 48a
• Chandra Detects the Rare Oxygen-type Wolf-Rayet Star WR 142 and OB Stars in Berkeley 87
• Chandra HETG Observations of the Colliding Stellar Wind System WR 147
• X-ray diagnostics of massive star winds
• Hard X-ray emission in the star-forming region ON2: discovery with XMM-Newton
• On the binary nature of massive blue hypergiants: high-resolution X-ray spectroscopy suggests that Cyg OB2 12 is a colliding wind binary
• Infrared identification of hard X-ray sources in the Galaxy
• Chandra Observations of the Massive Star-Forming Region Onsala 2
• X-ray emission of massive stars and their winds
• X-ray emission from massive stars with magnetic fields
• X-rays from the oxygen-type Wolf-Rayet binary WR30a
• Clustered star formation towards Berkeley 87 / ON2. I. Multi-wavelength census and the population overlap problem