the sws and lws will be used to provide complete spectral scans of a selected sample of r coronae borealis stars at full or near-full resolution. the energy distribution will be used to infer the distribution of dust with distance from the star and, in particular, to search for a distant cold shell that may have been ejected thousands of years earlier when the star was on the asymptotic giant branch. broad spectral features will betray the chemical make-up of the dust grains. emission lines from a circumstellar nebula may be present from atomic fine structure transitions (e.g., [o i] at 63 and 145 micron) and molecular pure rotation transitions (e.g., co high-j lines). the autumn sample of stars includes v854 cen with an unusually high hydrogen content for a rcb and v cra, both with highly anomalous si/fe and s/fe ratios. ry sgr having normal ratios serves as a comparison but is also of considerable intrinsic interest. the autumn list is completed with a hot rcb v348 sgr. the sole spring target is su tau known to have a distant cold shell. light may be shed on the origins of rcbs. stars formed from the merger of a he and c-o white dwarfs are unlikely to possess a distant cold dust shell but this characteristic is highly probable for a rcb formed as a .born again. agb star from a star on the white dwarf cooling track that ignites its he shell.
Instrument
LWS01 , SWS01
Temporal Coverage
1996-09-09T01:03:47Z/1997-03-25T15:58:59Z
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.
