The following document lists the file abstract/DROUAN_ENVLPPN.abs
from catalogue VI/111.
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SCIENTIFIC ABSTRACT This is the second part of a proposal on Planetary and Protoplanetary Nebulae that includes spectro-imaging and large scale imaging of circumstellar envelopes. This part aims mainly to the study of the outer envelope. Circumstellar envelopes of gas and dust around evolved stars can extend over several minutes, but become optically thin at short distance from the central star: using CAM, we propose to map in several wide band filters the outer part of the envelope of a selection of a few archetypical objects through the thermal dust emission and the scattered light: this would give access to: a) the history of the mass-loss on a much larger time scale than presently known; b) the structure of the non-symetric envelopes at a large distance. The second part, broad-band imaging of a selection of PNs, intends at completing the program of spectro-imaging by tentative detection at longest wavelength of a dusty disk and envelope around PNe and PPNe. OBSERVATION SUMMARY Part 1: Extended envelopes of PPNs: Sources: - OH231.8+4.2: an OH source with very distinctive properties: an extended bipolar structure with a pronounced waist, a strong ice absorption feature at 3.05 microns, and a large terminal velocity of the outflow; - IRAS 09371+1212 (Frosty Leo nebula): the most icy envelope known today, shows a disk and a weakly collimated very cold (T < 45K) bipolarity; - CRL 2688 (egg nebula): the prototype of a collimated extended bipolar nebula, with evidence for a bipolar cavity, and differing from the previous one by C/O > 1; - CIT-6: a prototype of close carbon star with a thick envelope. Proposed observations: AOT: General Observation : Filter LW9, LW10, SW4, SW5. PFOV = 1.5 or 3 arcsec. Complete integration time per filter: 15 to 30 min. The longer the integration time, the larger the radial distance of the probed region: angular radial distance of typically 40 arc-sec will be reached with the sensitivity of CAM. The elementary integration time is chosen to have the pixel of maximum signal at the limit of saturation. Part 2: Broad-band imaging of PNe Sources: Classical PNe and PPNe corresponding to the previous part and to the program of spectro-imaging by P. Persi et al.: IC 418, a classical PN; HD 44179, a bipolar PPN (= Red Rectangle); NGC2346, another bipolar PPN; NGC 6302, a bipolar PN; NGC 6720, an extended PN with ring; NGC 7027, the archetypal young PN. It is proposed to perform images at 15 microns to detect the presence of a dusty disk and to study the distribution of cold dust. A rather short integration is sufficient since only the bright central part is of interest here. Proposed observation: AOT: General Observation, Filter LW9, LW10, PFOV = 1.5 arcsec