Searching for the Missing Mass in Very Young Preplanetary Nebulae

Details Searching for the Missing Mass in Very Young Preplanetary Nebulae Searching for the Missing Mass in Very Young Preplanetary Nebulae

Jun 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005sptz.prop20590s&link_type=abstract

Spitzer Proposal ID #20590

Physics

Scientific paper

Pre-Planetary nebulae (PPNe), objects in transition between the AGB and planetary nebula (PN) evolutionary phases, hold the key to our understanding of the late evolutionary stages of low and intermediate mass stars. Essentially all well-characterized PPNe are bipolar, whereas the mass-loss envelopes of AGB stars are strikingly spherical -- we find that almost all the targets observed in our HST surveys of young PPNe (yPPNe) which are resolved, show well-defined bipolar or multipolar morphologies. We have hypothesized that it is the hydrodynamic interaction of fast, tenuous collimated flows with the dense, cool massive envelope ejected during the AGB phase, which is responsible for shaping these objects. The bulk of the nebular mass in this envelope, is however not seen in the HST data, since much of it resides in a cool, dusty, molecular component surrounding the central aspherical nebula. Thus a crucial ingredient for theoretical studies of such interactions is lacking for a majority of the yPPNe discovered in our HST surveys. We propose to use IRAC, IRS & MIPS to characterise the infrared spectrum of a selected sample (16) of such objects from short to long wavelengths, as a primary probe of the total circumstellar mass. Detailed spectra and full SEDs are necessary in order to derive the total dust mass, which depends sensitively on the radial temperature distribution and can only be determined accurately by modeling the full infrared spectrum of these objects. Our spectra should also show specific dust features (e.g. silicate feature in absorption) which act as probes of different structural components (e.g. a central equatorial disk) and unusual physical processes (e.g. growth of icy grain mantles) in these objects, and constrain uncertainties in the dust properties (emissivity law, composition), which also affect the mass determination.

Affiliated with

Also associated with

No associations

Rating

Searching for the Missing Mass in Very Young Preplanetary Nebulae does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Searching for the Missing Mass in Very Young Preplanetary Nebulae, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Searching for the Missing Mass in Very Young Preplanetary Nebulae will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1167391