http://arxiv.org/abs/1805.10599
We present JCMT SCUBA-2 $450\mu$m and $850\mu$m observations of 14 Asymptotic Giant Branch (AGB) stars (9 O–rich, 4 C-rich and 1 S–type) and one Red Supergiant (RSG) in the Solar Neighbourhood. We combine these observations with \emph{Herschel}/PACS observations at $70\mu$m and $160\mu$m and obtain azimuthally-averaged surface-brightness profiles and their PSF subtracted residuals. The extent of the SCUBA-2 850 $\mu$m emission ranges from 0.01 to 0.16 pc with an average of $\sim40\%$ of the total flux being emitted from the extended component. By fitting a modified black-body to the four-point SED at each point along the radial profile we derive the temperature ($T$), spectral index of dust emissivity ($\beta$) and dust column density ($\Sigma$) as a function of radius. For all the sources, the density profile deviates significantly from what is expected for a constant mass-loss rate, showing that all the sources have undergone variations in mass-loss during this evolutionary phase. In combination with results from CO line emission, we determined the dust-to-gas mass ratio for all the sources in our sample. We find that, when sources are grouped according to their chemistry, the resulting average dust-to-gas ratios are consistent with the respective canonical values. However we see a range of values with significant scatter which indicate the importance of including spatial information when deriving these numbers.
T. Dharmawardena, F. Kemper, P. Scicluna, et. al.
Tue, 29 May 18
26/73
Comments: 18 pages plus 13 pages of supplementary figures. Accepted for publication on MNRAS on 24/05/2018
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