000002835 001__ 2835
000002835 005__ 20160701171711.0
000002835 037__ $$aASTROimport-992
000002835 100__ $$aGroenewegen, M.
000002835 245__ $$aSDP_mgroen01_3: The circumstellar environment in post-main-sequence objects
000002835 260__ $$c2011
000002835 520__ $$aMass loss is one of the most fundamental properties of post-main sequence evolution. The mass-loss process leads to the formation of circumstellar shells containing dust and molecules. Although the mass-loss phenomenon has been studied since the 1960s, and important results have been obtained with the IRAS, ISO and Spitzer space missions, the details of the mass-loss process and the formation and evolution of the circumstellar shells are still not well understood. With its improved spatial resolution compared to ISO and Spitzer, better sensitivity, the extension to longer and unexplored wavelength regions, and medium resolution spectrometers, the combination of PACS and SPIRE observations will lead to a significant improvement in our understanding of the phenomena of mass loss and dust formation. The main aims of this programme are three-fold: (1) to study the time dependence of the mass loss process, via a search for shells and multiple shells around a wide range of evolved objects, in order to quantify the total amounts of mass lost at the various evolutionary stages of low to high-mass stars, (2) to study the dust and gas chemistry as a function of progenitor mass, and (3) to study the properties and asymmetries of evolved star envelopes. To this end, a sample of 103 Asymptotic Giant Branch and Red Super Giants, post-AGB and Planetary Nebulae, Luminous Blue Variables and Wolf-Rayet stars, and 5 Supernovae remnants will be imaged with PACS at 70+170 micron, and a sub-set of 32 stars will be imaged at all 3 wavelengths with SPIRE. In spectroscopy, a sample of 55 stars will be observed over the full wavelength range of PACS and, 23 stars will be observed with the SPIRE FTS. The sample of AGB stars has been selected to cover all chemical types (M-, S-, C-stars), variability types (irregular, semi-regular, Miras) and periods, and mass-loss rates. Stars have been selected to have high IRAS fluxes and low background levels.  The spectroscopic targets are typically the brightest of the mapping targets 
000002835 773__ $$c308$$pHerschel Space Observatory Proposal, id.308$$y2011
000002835 85642 $$ahttp://esoads.eso.org/abs/2011hers.prop..308G
000002835 905__ $$apublished in
000002835 980__ $$aNONREF