In this work we explore the possibility that the observed time variable emission at radio frequencies from the CEN 1a system has a thermal origin. The observed flux densities and spectral indices from this source clearly deviate from the standard stellar wind model around a massive star, and seem to be consistent with optically-thin thermal emission. Here we investigate the radio-continuum free-free emission from a stellar wind with time-dependent injection parameters, which result in the formation of internal shocks that travel away from the central star. Although our model is able to predict the observed flux densities and spectral indices from the CEN 1a source, it fails to explain the detected variability in the optically-thin regime. We conclude that the observed emission has a composite nature, with thermal and non-thermal contribution.
Revista Mexicana de Astronomia y Astrofisica
- Pub Date:
- April 2013
- radiation mechanisms: thermal;
- radio-continuum: ISM;
- shock waves;
- stars: individual (CEN 1a)