| Description |
..Water fountain. stars (WF) are considered key objects to our knowledge of
the sun-like star evolution processed. At some point soon after AGBs, WFs would
develop very fast and highly-collimated outflows, which produces H _2 O maser
emission, spread over more than 100,kms, when hitting the AGB previous envelope.
Very recently, our group has detected low- J CO and ^{13} CO line emission
arising in the cold, outer parts of the envelope. Based on these results, we ask
for HIFI observations of mid- and high- J lines of CO, together with a set of
thermal H _2 O lines, and CI. With these data, we plan to probe the inner, hotter,
and denser parts of the envelopes, and to give some insights about the mass-loss
history and chemistry; possibles PDRs will also be tested. This information will
provide valuable inputs to our models, such as the total mass, and temperature
profile. Some physical parameters will be also constrained. We have selected the
whole sample of known WFs, a total of 14 sources (two of them still unpublished),
for this project. |
