the goal of this proposal is to determine the chemical properties of the dust shells of proto-planetary nebulae (ppn) through a study of their short-wavelength, and in a few cases their long-wavelength, infrared spectra. spectral features in the 10 to 20 micron region indicate the chemical nature (oxygen or carbon-rich), and the strengths of the features relate to the physical properties of the shells. a few bright carbon-rich ppn have been observed to show pah features and an unidentified 21 micron emission feature. we propose to observe a sample of iras sources which have the expected properties of ppn and for which we have confirmed a visible counterpart. these we have observed extensively from the ground - visible photometry, near- infrared photometry, visible spectroscopy - and are well prepared to interpret the infrared spectra of these objects in the context of their overall properties. this study will greatly advance our understanding of this important evolutionary stage. only iso provides the spectral range and resolution necessary to carry out these observations.
Instrument
LWS01 , SWS01
Temporal Coverage
1996-05-20T02:11:07Z/1997-10-01T19:06:54Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
