SIMBAD references

2008A&A...490..259S - Astronomy and Astrophysics, volume 490, 259-264 (2008/10-4)

Redshifted emission lines and radiative recombination continuum from the Wolf-Rayet binary θ Muscae: evidence for a triplet system?


Abstract (from CDS):

We present XMM-Newton observations of the WC binary θ Muscae (WR 48), the second brightest Wolf-Rayet binary in optical wavelengths. The system consists of a short-period (19.1375days) WC5/WC6 + O6/O7V binary and possibly has an additional O supergiant companion (O9.5/B0Iab) which is optically identified at a separation of ∼46mas. Strong emission lines from highly ionized ions of C, O, Ne, Mg, Si, S, Ar, Ca and Fe are detected. The spectra are fitted by a multi-temperature thin-thermal plasma model with an interstellar absorption NH=2-3x1021cm–2. Lack of nitrogen line indicates that the abundance of carbon is at least an order of magnitude larger than that of nitrogen. A Doppler shift of ∼630km/s is detected for the O VIII line, while similar shifts are obtained from the other lines. The reddening strongly suggests that the emission lines originated from the wind-wind shock zone, where the average velocity is ∼600km/s. The red-shift motion is inconsistent with a scenario in which the X-rays originate from the wind-wind collision zone in the short-period binary, and would be evidence supporting the widely separated O supergiant as a companion. This may make up the collision zone be lying behind the short-period binary. In addition to the emission lines, we also detected the RRC (radiative recombination continuum) structure from carbon around 0.49keV. This implies the existence of additional cooler plasma.

Abstract Copyright:

Journal keyword(s): X-rays: stars - stars: Wolf-Rayet - binaries: spectroscopic - stars: winds, outflows - stars: individual: HD113904

Status at CDS:  

Simbad objects: 5

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