| |
 |
| Paper: |
Probing Circumstellar Environments with Combined H I and CO Observations |
| Volume: |
445, Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants |
| Page: |
275 |
| Authors: |
Libert, Y.; Le Bertre, T.; Gérard, E.; Winters, J. M.; Matthews, L. D. |
| Abstract: |
Circumstellar shells around red giants are built over long periods of time
that may reach several million years. They may therefore be extended over
large sizes (∼ 1 pc, possibly more) and different tracers are needed
to describe their global properties. We designed a program to gauge the
properties of matter in the external parts of circumstellar shells around
AGB stars and to relate them to those of the inner envelopes, using the
complementarity of the 21-cm H I line and the CO rotational
lines.
With millimeter observations at high spatial resolution, we find structures
that could be the precursors of the complex morphologies observed for
several planetary nebulae. Thanks to the 21-cm observations, we found
evidence that the gas outflow is slowed down by the ambient interstellar
medium. In some cases, the H I source
is elongated in a direction compatible with the central-star
proper motion, a phenomenon that is being recognized more and
more often and that suggests an interaction with the local material.
We illustrate these properties with several objects that have been well
observed in CO and H I. |
|
|
|
|
|
