The following document lists the file abstract/DLAMBERT_DLL001.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
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.