A multi-wavelength view on the dusty Wolf-Rayet star WR 48a

TL;DR

This study provides a comprehensive multi-wavelength analysis of the dusty Wolf-Rayet star WR 48a, revealing its physical properties, spectral composition, distance, and variability across optical, radio, and X-ray observations.

Contribution

It introduces the first multi-wavelength characterization of WR 48a, combining optical, infrared, radio, and X-ray data to derive its physical parameters and variability.

Findings

WR 48a is located at approximately 4 kpc distance.

The optical spectrum is a combination of WC8 and WN8h types.

WR 48a exhibits long-term variability in optical, radio, and X-ray bands.

Abstract

We present results from the first attempts to derive various physical characteristics of the dusty Wolf-Rayet star WR 48a based on a multi-wavelength 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 (dM/dt = a few x 10^(-4) solar masses per year). Long timescale (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 LBV-like (luminous blue variable) activity could not be excluded as well.