Revealing the transition from post-AGB stars to planetary nebulae: non-thermal and thermal radio continuum observations |
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| Authors: | I Bains M Cohen J M Chapman R M Deacon M P Redman |
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| Institution: | Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia;Radio Astronomy Laboratory, University of California, Berkeley, CA 94720, USA;Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia;School of Physics A29, University of Sydney, Sydney, NSW 2006, Australia;Centre for Astronomy, School of Physics, National University of Ireland, University Road, Galway, Ireland |
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| Abstract: | Midcourse Space eXperiment and Infrared Astronomical Satellite colour diagnostics as well as OH maser profile characteristics were used to select a sample of post-asymptotic giant branch (pAGB) candidates for a radio continuum detection experiment with the Australia Telescope Compact Array. Seven out of 28 sources, six of which are new detections, show a continuum. A planetary nebula serendipitously detected in the field of an undetected pAGB candidate also reveals radio continuum. The radio continuum properties of these eight sources are described. Almost half have non-thermal emission. dusty modelling of the infrared spectral energy distributions (SEDs) of the three strongest detections reveals that they all have central stars with temperatures substantially lower than that required for significant photoionization, leading us to infer that the radio continuum has arisen from wind–shock interactions. This hypothesis is consistent with the detection of non-thermal radio emission in one of these three objects. |
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| Keywords: | masers stars: AGB and post-AGB stars: late-type stars: winds outflows radio continuum: stars |
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