MERLIN observations of the Wolf–Rayet star AS431 (WR147)-a double radio source

New interferometric observations of the Wolf-Rayet star AS431 using the MERLIN network are presented. These observations had a sensitivity sufficient to map the stellar-thermal continuum radio emission with a beam size of 0.1 arcsec. The object is resolved into two radio source separated by 0.6 arcsec, corresponding to a spatial separation of 1100 AU at the assumed distance of 1.9 kpc. The computed brightness for the two sources, about 10,000 K, is typical of optically thick thermal emission from a stellar wind, and suggests that some part of the emission is nonthermal. One of the radio components corresponds to the position of the single source revealed by accurate optical observations. The observed total radio spectrum is simulated with a two-component model for the emission.

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