========================================================================
==> In this proposal, more time is being requested for HWALKER.RCRBFOS1
========================================================================
The aim of this proposal is to investigate fossil dust shells around
members of the class of R CrB stars, following the discovery, using
IRAS, of a very large cool dust shell around R CrB itself, and
possibly one around SU Tau. The parameters of the R CrB dust shell
are very uncertain, but they are not inconsistent with the
evolutionary scenario for R CrB. The original IRAS data suggested
that not all R CrB stars might have this cool fossil shell, so that
a more sensitive survey of the stars is needed. Since the fossil
shells are only visible at 60um and 100um with IRAS, only ISO can
further investigate the phenomenon. The dust temperature was estimated
at 25 - 30 K. The size of the fossil shell around R CrB was about
20 arcmin, so that sparse mapping is needed.
Time was awarded in the pre-launch call to make maps of 2 targets and
do multi-aperture photometry of a 3rd target, time to observe more
targets is requested.