A multiwavelength view on the dusty Wolf–Rayet star WR 48a★

Abstract

We present results from the first attempts to derive various physical characteristics of the dusty Wolf–Rayet (WR) star WR 48a based on a multiwavelength view of its observational properties. This is done on the basis of new optical and near-infrared spectral observations and on data from various archives in the optical, radio and X-rays. The optical spectrum of WR 48a is acceptably well represented by a sum of two spectra: of a WR star of the WC8 type and of a WR star of the WN8h type. The strength of the interstellar absorption features in the optical spectra of WR 48a and the near-by stars D2-3 and D2-7 (both members of the open cluster Danks 2) indicates that WR 48a is located at a distance of ∼4 kpc from us. WR 48a is very likely a thermal radio source and for such a case and smooth (no clumps) wind its radio emission suggests a relatively high mass-loss rate of this dusty WR star (⁠|$\dot{M} \approx \mbox{a few} \times 10^{-4}$| M⊙ yr−1). Long time-scale (years) variability of WR 48a is established in the optical, radio and X-rays. Colliding stellar winds likely play a very important role in the physics of this object. However, some luminous blue variable like activity could not be excluded as well.