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==> In this proposal, more time is being requested for LFERETTI.CLG_STR
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This proposal is a completion and extension of a previously approved one to
observe a sample of elliptical galaxies belonging to rich clusters, and study
the effect of ram-pressure stripping on the cold component of the
interstellar medium. Previous observations, obtained with ISO gave very
important results, but are not enough for a statistical study, because of
the limited  allocated observing time.
Galaxies moving in dense environment are expected to be stripped, either
through encounters with other galaxies, or by interaction with the
intracluster medium. The ram-pressure effect causes removal of interstellar
medium material from the outer parts of the galaxy, while the gas and dust
surviving in the innermost parts are expected to be warmer and denser.
The best candidates for the study of ram-pressure stripping effects are
cluster radio galaxies showing a tailed morphology, since the radio
structure of these objects demonstrates the interaction of the parent galaxy
with the intergalactic medium. To avoid a bias toward radio emitting
galaxies, we also request to observe a sample of radio-quiet cluster
galaxies, moving  at high speed with respect to the cluster mean velocity,
i.e. objects where  the stripping effects are expected to be strong.
Our sample consists of elliptical galaxies belonging to 3 rich clusters:
A2151, A1656 and A2255. The galaxies in A2151 were partly observed with
our previous ISO proposal. We note that in A1656 only the spiral galaxies
have been observed so far with ISO, while no data on the ellipticals have
been obtained.
We request photometric observations at 3 wavelengths, to derive the mass and
temperature of the dust, and CAM observations at 15 micron to get
information on the spatial distribution of the dust with respect  to the
galaxy.