On the apparent absence of WR+NS systems: the curious case of WR124

Abstract

Among different types of massive stars in advanced evolutionary stages is the enigmatic WN8h type. There are only a few Wolf-Rayet (WR) stars with this spectral type in our Galaxy. It has long been suggested that WN8h-type stars are the products of binary evolution that may harbor neutron stars (NS). One of the most intriguing WN8h stars is the runaway WR124 surrounded by its magnificent nebula M1-67. We test the presence of an accreting NS companion in WR124 using 100 ks long observations by the Chandra X-ray observatory. The hard X-ray emission from WR124 with a luminosity of $L_{\mathrm{X}}$= 10${}^{31}$ erg s${}^{-1}$ is marginally detected. We use the non-LTE stellar atmosphere code PoWR to estimate the WR wind opacity to the X-rays. The wind of a WN8-type star is effectively opaque for X-rays, hence the low X-ray luminosity of WR124 does not rule out the presence of an embedded compact object. We suggest that, in general, high opacity WR winds could prevent X-ray detections of embedded NS, and be an explanation for the apparent lack of WR+NS systems.

arXiv comment7 pages; 1 Table; 3 Figures; to appear in ApJ Letters

References in corpus (27)

• The Supernova -- Gamma-Ray Burst Connection
• The Evolution of Compact Binary Star Systems
• The Galactic WN stars: Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation
• Common Envelope Evolution Leading to Supernovae with Dense Interaction
• Forming short-period Wolf-Rayet X-ray binaries and double black holes through stable mass transfer
• Astrophysical supplements to the ASCC-2.5. Ia. Radial velocities of about 55000 stars and mean radial velocities of 516 Galactic open clusters and associations
• The Dynamics and Outcomes of Rapid Infall onto Neutron Stars
• Dynamical ejections of massive stars from young star clusters under diverse initial conditions
• Towards a unified view of inhomogeneous stellar winds in isolated supergiant stars and supergiant high mass X-ray binaries
• Asymmetric Accretion Flows within a Common Envelope
• Spatial distribution of Galactic Wolf-Rayet stars and implications for the global population
• Wolf-Rayet stars in the Small Magellanic Cloud: II. Analysis of the binaries
• Clumped stellar winds in supergiant high-mass X-ray binaries: X-ray variability and photoionization
• Three Dimensional Radiation Hydrodynamic Simulations of Massive Star Envelopes
• The Conspicuous Absence of X-ray Emission from Carbon-Enriched Wolf-Rayet Stars
• Cygnus X-3 and the problem of the missing Wolf-Rayet X-ray binaries
• A Morphological Diagnostic for Dynamical Evolution of Wolf-Rayet Bubbles
• The hypersoft state of Cygnus X-3 - A key to jet quenching in X-ray binaries?
• Two extremely luminous WN stars in the Galactic center with circumstellar emission from dust and gas
• Clumpy wind accretion in supergiant neutron star high mass X-ray binaries
• New X-ray Detections of WNL Stars
• Hot gas in the Wolf-Rayet nebula NGC3199
• Absence of hot gas within the Wolft-Rayet Bubble around WR16
• Population I Wolf-Rayet Runaway Stars: the Case of WR124 and its Expanding Nebula M1-67
• A 10-hour period revealed in optical spectra of the highly variable WN8 Wolf-Rayet star WR 123
• WR 148: Identifying the companion of an extreme runaway massive binary
• Integral field spectroscopy of M1-67. A Wolf-Rayet nebula with LBVN appearance

Cited by in corpus (14)

• The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters
• The stellar and wind parameters of six prototypical HMXBs and their evolutionary status
• An absence of binary companions to Wolf-Rayet stars in the Small Magellanic Cloud: implications for mass loss and black hole masses at low metallicity
• Non-thermal radio supernova remnants of exiled Wolf-Rayet stars
• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars. III. The northern late-type nitrogen-rich sample
• On the ring nebulae around runaway Wolf-Rayet stars
• On the bipolarity of Wolf-Rayet nebulae
• The Bubble Nebula NGC 7635 -- testing the wind-blown bubble theory
• Dust in the Wolf-Rayet Nebula M1-67
• Dust in RCW 58: clues to common envelope channel formation?
• 3D mapping of the Wolf-Rayet nebula M1-67: clues for post-common envelope evolution in massive stars
• A Radio Pinwheel Emanating from WR147
• Multiple variability time-scales of the early nitrogen-rich Wolf-Rayet star WR7
• New insights into the WR nebula M1-67 with SITELLE