==> This is a continuation and ISO follow up of proposal RSIEBENM.RSIEHEBE
==> We request more observing time.
==> 11061s grade 6 and 7199 grade 8 time for this proposal is to be
==> transferred from RSIEBENM.RSIEHEBE.
We propose to study extended emission of intermediate mass pre-main
sequence stars. We have selected a sample of nearby Herbig Ae/Be
stars. We will investigate the contribution of individual dust
populations (large grains, small graphites, PAH) to the overall
energetics of the halo. For this end, the well known mid IR excess of
the objects will be imaged at different CVF positions.  The detailed
picture of the circumstellar environment will be used to disentangle
the luminosity of the disk and envelope.  Our radiative transfer
models will be constrained by far IR maps.  Out of these maps we will
derive physical parameters such as far IR sizes, colour temperatures,
total dust mass, density distributions and opacities.
One of our target (HD97300) has been observed and show the predicted
extended emission. The CAM images show an unpredicted spectacular ring
emission surrounding HD97300 (see Figure). The ring can be explained
by means of radiative transfer models including small grain
components.  However, a direct proof of the presence of small grains
will only come from the here requested additional CVF scan on the
ring. In order to probe unambiguously the predicted extended emission
we request additional narrow band images in PAH filter LW4 and
reference filter LW5. We ask for observing time for two additional
targets from our spring list and a compensation for ~20% higher
overheads in our P32 observations as compared to phase 1 submission of
the first ISO CALL.