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| Paper: |
The Circumstellar 12CO/13CO Ratio in
AGB Stars of Different Chemical Type |
| Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
| Page: |
295 |
| Authors: |
Olofsson, H.; Ramstedt, S. |
| Abstract: |
We have investigated the evolution of the 12C/13C ratio along
the AGB through the circumstellar isotopologue 12CO/13CO
abundance ratio for a significant number of M-, S-, and C-type AGB stars.
The isotopologue ratios are estimated through a detailed radiative
transfer analysis of single-dish radio-line observations. The
circumstellar 12CO/13CO ratio differs between the three
spectral types; the median values are 13, 26, and 34 for the M-, S-type,
and carbon AGB stars, respectively, consistent with what is expected
from stellar evolutionary models assuming that the spectral types
constitute an evolutionary sequence. The spread of the abundance ratio
among carbon stars is much larger than for the other chemical types.
We find no correlation between the isotopologue ratio and the mass-loss
rate. |
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