| Description |
Evolved stars are the birthplaces of the interstellar gas and solid dust particles. Such stars lose mass through
a stellar wind, which is slow and dusty for cool giants and supergiants, or through impressive supernova explo-
sions. However, recent observations with the PACS and SPIRE photometers reveal that the encounter between
these slow and dusty winds and the interstellar medium is as spectacular as supernova explosions: multiple arcs,
bar-like structures and different kind of instabilities (Rayleigh-Taylor and Kelvin-Helmholtz) are detected. The
most outstanding example concerns the well-known supergiant Betelgeuse. However, with the current set of
Herschel observations, it is impossible to dene the exact physical mechanism causing the observed infrared
emission. We propose to obtain PACS [O I] and HIFI [C II] spectroscopic observations at different pointings in
the turbulent wind interaction zone around Betelgeuse. The proposed DDT observations would only take 3.1 hr
and would give the astronomical community the rst possibility to study spectroscopically the different dynam-
ical and chemical processes partaking in the interaction zone between circumstellar and interstellar material.
The derived spectroscopic information will be valuable to the whole community in preparation of OT2. |
