reflection nebulae (rns) are objects of special interest because they provide an opportunity to explore the interaction of a single star with a region of high density ism.they are bright enough to permit a detailed spectroscopy of the emission by is dust and gas . in addition, the characteristics of the stellar radiation incident can vary from object to object (o/b to m stars), allowing tests of specific models for the excitation of different is species. our proposal will use iso to study a sample of rns illuminated with widely varying temperatures. we propose to obtain: - complete 2.5-200 um spectra for a subset of rns with varying stellar temperature. this is the heart of the proposal. - 3-200 um broad band energy distributions of the emission for all rns. - measurement of the gas heating efficiency for a subset of rns, by varying(i) the irradiation spectra (o/b to m stars) and (ii) the flux intensity (different distances from the star in a given rn). specifically, we want to: - confirm or deny the pah hypothesis;if confirmed, make a more specific identification of the molecular species and correlate their ionization and dehydrogenation states with the stellar irradiation. - search for c60 molecules or ions. - look for spectral features that could identify the particles emitting by temperature fluctuations in the 20-100 um range, because, presently, we know nothing on their chemical nature. - determine whether there is a cut-off in the exciting star temperature underwhich the gas heating efficiency drops, as expected if the heating mechanism is photoelectric effect.
Instrument
PHT17 , PHT18 , PHT19
Temporal Coverage
1996-06-07T13:21:38Z/1996-06-07T13:42:38Z
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.
