The promise for AGB stars: Physics and chemistry of the inner circumstellar envelope, and the mass loss history

Autor(en)

Franz Kerschbaum, Hans Olofsson

Abstrakt

The Herschel HIFI heterodyne spectrometer and the PACS imaging/spectrometer instruments will provide important information on the physical and chemical conditions in the inner circumstellar envelopes of AGB-stars, e.g., on the rotational lines of the important coolants CO, HCN, and H2O, and on various molecular species that participate in the initial chemistry of the escaping gas. Dynamical studies in the acceleration zone will be possible with HIFI, too. ISO was limited to high mass loss rate and/or very nearby objects and did not allow high resolution heterodyne spectra. Ground-based observatories cannot study most of the crucial far-infrared and sub-mm domains. The solid state features of circumstellar dust particles are mainly found in the near- and mid-infrared ranges, although a crystalline water-ice feature at 62œm has been seen towards early post-AGB objects, planetary nebulae, Herbig Ae/Be stars, and Herbig-Haro objects. Most ISO observations in these ranges were suffering from too low S/N-ratios. The sensitivity of Herschel is superior, but the short wavelength end of PACS may limit what can be achieved in this area. The temporal variation of the mass loss rate is to a large extent unknown. This applies to all time scales from the pulsation period to the full time scale of the AGB-phase. Extended dust emission observed with PACS, perhaps in combination with Herschel-SPIRE, will provide important results on the long-term mass loss history.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Stockholm Observatory

Journal

European Space Agency, Special publications: ESA - SP

Band

460

Seiten

245-247

Anzahl der Seiten

3

ISSN

0379-6566

Publikationsdatum

2001

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/the-promise-for-agb-stars-physics-and-chemistry-of-the-inner-circumstellar-envelope-and-the-mass-loss-history(942a6aef-4400-4df7-9b74-1901a8d88e94).html