Contents of: VI/111/./abstract/PAPPLETO_PROP_1.abs

The following document lists the file abstract/PAPPLETO_PROP_1.abs from catalogue VI/111.
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We propose deep imaging of two collisonal ring galaxies in 4 mid-IR
bands of ISOCAM in order to map the distribution of dust in these
galaxies. Ring galaxies are believed to be formed when a small
companion galaxy plunges through the center of a rotating disk
system, driving radially expanding waves into the disk. These waves
have been shown to trigger star formation as they pass through the
disk. Ring galaxies, through their special dynamical
properties are therefore remarkable laboratories for studying the
evolution of young massive star clusters formed in collisions.
Ring galaxies exhibit unusually high local star formation rates
comparable to those seen in the nuclei of starburst galaxies. Unlike
these more complicated cousins, the  ring starbursts have a well
defined history dictated by the propagation velocity of the ring.
Typical rings expand through the disk in a few hundred million years
leaving a trail of evolving star clusters in their wake. This effect,
which was predicted by numerical models, has been recently observed
to produce unusually large radial color gradients within the rings.

Our observations will provide the first high sensitivity images
of two molecular-rich  classical ring galaxies, NGC 985 and VIIZw466.
The observations will allow for the first time the detailed
distribution of dust to be imaged and compared with CO maps, radio
continuum, optical and near IR images of the systems. We expect
to detect dust not only within the bright star forming rings,
but possibly also from inside the ring, where in at least one
case, large quantities of molecules reside. Attempts to detect
the rings from the ground at 5 microns failed because of the
relatively faint nature of the emission. ISO is the ideal
instrument for our project.