Wind clumping and the wind-wind collision zone in the Wolf-Rayet binary gamma Velorum

Abstract

We present XMM-Newton observations of gamma^2 Velorum (WR 11, WC8+O7.5III, P = 78.53 d), a nearby Wolf-Ray binary system, at its X-ray high and low states. At high state, emission from a hot collisional plasma dominates from about 1 to 8 keV. At low state, photons between 1 and 4 keV are absorbed. The hot plasma is identified with the shock zone between the winds of the primary Wolf-Rayet star and the secondary O giant. The absorption at low state is interpreted as photoelectric absorption in the Wolf-Rayet wind. This absorption allows us to measure the absorbing column density and to derive a mass loss rate 8x10^{-6} M_sun/yr for the WC8 star. This mass loss rate, in conjunction with a previous Wolf-Rayet wind model, provides evidence for a clumped WR wind. A clumping factor of 16 is required. The X-ray spectra below 1 keV (12 Ang) show no absorption and are essentially similar in both states. There is a rather clear separation in that emission from a plasma hotter than 5 MK is heavily absorbed in low state while the cooler plasma is not. This cool plasma must come from a much more extended region than the hot material. The Neon abundance in the X-ray emitting material is 2.5 times the solar value. The unexpected detection of CV (25.3 Ang) and CVI (31.6 Ang) radiative recombination continua at both phases indicates the presence of a cool (~40,000 K) recombination region located far out in the binary system.

16 pages

References in corpus (11)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• A Grid of NLTE Line-Blanketed Model Atmospheres of O-type Stars
• High resolution X-Ray spectroscopy of Zeta Puppis with the XMM-Newton Reflection Grating Spectrometer
• Chandra Discovers a Very High Density X-ray Plasma on the O-Star Zeta Orionis
• Quantitative analysis of WC stars: Constraints on neon abundances from ISO/SWS spectroscopy
• The X-Ray Spectrum and Global Structure of the Stellar Wind in Vela X-1
• Detection of Doppler Shifted X-ray Line Profiles from the Wind of Zeta Puppis (O4f)
• The Conspicuous Absence of X-ray Emission from Carbon-Enriched Wolf-Rayet Stars
• X-ray Line Emission from the Hot Stellar Wind of theta 1 Ori C
• Fundamental stellar parameters of zeta Pup and gamma^2 Vel from HIPPARCOS data
• Blobs in Wolf-Rayet Winds: Random Photometric and Polarimetric Variability

Cited by in corpus (48)

• Physical Properties of Wolf-Rayet Stars
• X-Ray Spectroscopy of Stars
• Low mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
• Probing clumpy stellar winds with a neutron star
• Non-thermal high-energy emission from colliding winds of massive stars
• Catalogue of particle-accelerating colliding-wind binaries
• High resolution X-ray spectroscopy of bright O type stars
• Evolution of X-ray emission from young massive star clusters
• The Interplay between Star Formation and the Nuclear Environment of our Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet Clusters
• 3D models of radiatively driven colliding winds in massive O+O star binaries - III. Thermal X-ray emission
• Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations
• X-ray emission from interacting massive binaries: a review of 15 years of progress
• Asphericity and clumpiness in the winds of Luminous Blue Variables
• A compact pulsar wind nebula model of the gamma-ray loud binary LS I +61 303
• Fe emission and ionized excess absorption in the luminous quasar 3C109 with XMM-Newton
• Effects of the stellar wind on X-ray spectra of Cygnus X-3
• X-ray Emission from Nitrogen-Type Wolf-Rayet Stars
• The Fermi LAT view of the colliding wind binaries
• X-rays from Colliding Stellar Winds: the case of close WR+O binary systems
• Colliding Stellar Winds Structure and X-ray Emission
• A VLT/FLAMES survey for massive binaries in Westerlund 1. III. The WC9d binary W239 and implications for massive stellar evolution
• New X-ray Detections of WNL Stars
• Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra
• The X-ray emission of Be+stripped star binaries
• Photoionization Emission Models for the Cyg X-3 X-ray Spectrum
• First detection of phase-dependent colliding wind X-ray emission outside the Milky Way
• Suzaku monitoring of the Wolf-Rayet binary WR140 around periastron passage: An approach for quantifying the wind parameters
• Identification of the Infrared Counterpart to a Newly Discovered X-ray Source in the Galactic Center
• XMM-Newton Observations Reveal Very High X-ray Luminosity from the Carbon-rich Wolf-Rayet Star WR 48a
• Numerical simulations and infrared spectro-interferometry reveal the wind collision region in gamma2 Velorum
• Chandra Detects the Rare Oxygen-type Wolf-Rayet Star WR 142 and OB Stars in Berkeley 87
• The variability of the BRITE-est Wolf-Rayet binary, ${\gamma }^2$ Velorum I. Photometric and spectroscopic evidence for colliding winds
• 3D magneto-hydrodynamic models of non-thermal photon emission in the binary system ${\gamma }^2$ Velorum
• XMM-Newton X-ray Observations of the Wolf-Rayet Binary System WR 147
• Competitive X-ray and Optical Cooling in the Collisionless Shocks of WR 140
• Redshifted emission lines and radiative recombination continuum from the Wolf-Rayet binary theta Muscae: evidence for a triplet system?
• Narrow Radiative Recombination Continua: A Signature of Ions Crossing the Contact Discontinuity of Astrophysical Shocks
• Is the stellar system WR 11 a gamma-ray source?
• Puzzling X-rays from the new colliding wind binary WR65
• Mixing of hot shocked plasma with cold gas in Nova YZ Ret 2020
• An X-ray view of HD166734, a massive supergiant system
• Chandra Observations of the Massive Star-Forming Region Onsala 2
• A Chandra Observation of the Eclipsing Wolf-Rayet Binary CQ Cep
• Long-term X-ray variation of the colliding wind Wolf-Rayet binary WR 125
• X-rays from the oxygen-type Wolf-Rayet binary WR30a
• The Outer Wind of gamma Velorum
• Variability in X-ray line ratios in helium-like ions of massive stars: the radiation-driven case
• On the orbital variability of gamma-ray emission in ${\gamma }^2$ Velorum