> in this proposal, more time is being requested for skwok.21micron > this proposal requests an upgrade from priority 3 for skwok.21micron the iras satellite discovered a small number of sources with an unidentified emission feature at 21 microns (kwok, volk, and hrivnak, 1989). currently this feature has been confirmed only in f- and g-type supergiant stars with large infrared excesses, and almost all 21 micron sources have been identified as stars in the transition from the asymptotic giant branch to the planetary nebula phase. although many suggestions have been made on the possible carrier of this feature, its origin remains unknown. optical spectroscopy of the stars with the 21 micron feature has shown that they are carbon-rich, and most of them display the strong near-infrared pah bands but their band ratios are different from other pah sources. in this proposal, we request iso observations to (1) confirm new 21 micron sources which we have selected from previous ground-based observations; and (2) to obtain high spectral resolution observations to search for possible fine structures in this broad feature. these observations will provide solid constraints on any dust carrier molecule and we hope that it will lead to an eventual identification of its carrier.
Instrument
SWS06
Temporal Coverage
1997-09-28T00:57:21Z/1997-11-03T06:18:49Z
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.
European Space Agency, 1999, A Detailed Study Of The Unidentified 21 Micron Emission Feature In Post-Agb Stars, 1.0, European Space Agency, https://doi.org/10.5270/esa-ee5f8ou
