Other
Scientific paper
Dec 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997hst..prop.7286o&link_type=abstract
HST Proposal ID #7286
Other
Hst Proposal Id #7286 Stellar Ejecta
Scientific paper
Previous HST imaging of the Helix Nebula, the closest of the representatives of this important stage of stellar evolution, have revealed that the filaments originally discovered by Baade are actually cometary outline photoionized regions surrounding dusty knots. The masses of the neutral knots are characteristically a few times 10^-5Msun. The ionized zones are many orders of magnitude less massive and trail out to cylindrical tails pointed exactly away from the Central Star. The origin of these objects is uncertain, with models ranging from Rayleigh-Taylor instabilities in the nebular material, through condensations in the precursor star atmosphere, to having Oort Cloud type origins when the Central Star formed. The proposed observations will perform spectrophotometry of the ionized portions of two Cometary Knots in order to accurately determine the density and temperature variations as a function of distance from the local ionization front, which will lead to an accurate model of these ionized zones and should allow the identification of whether or not the Cometary Knots are likely to survive the Planetary Nebula stage. Coordinated parallel imaging with the WFPC2 and NICMOS will also be done. The former will be used to more accurately determine the distribution of the dust in the neutral knots and to search for new Cometary Knots in the outer part of the nebula, and the latter will be used to search for FeII and Hrm_2 emission from other neutral knots.
No associations
LandOfFree
Spectrophotometry and Imaging of Cometary Knots in the Helix Nebula 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 Spectrophotometry and Imaging of Cometary Knots in the Helix Nebula, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spectrophotometry and Imaging of Cometary Knots in the Helix Nebula will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-895375