DUST IN COOLING FLOWS PRODUCTION AND DESTRUCTION OF DUST IN X-RAY GAS ENVIRONMENTS

iras data have been able to demonstrate the presence of dust in the icm (inter cluster medium) connected with a few dominant galaxies centered in cooling flows of xray emitting gas. the grains are predominantly heated by the bombardment of fast electrons. the firemission from the grains therefore becomes a sensitive probe of the temperature and density of the hot gas. because the grains are destroyed by sputtering on a short time scale (about 10e7 yr), the mere presence of dust calls for an explanation. in some cases (ngc4696) dust may have been accreted from outside, but in other cases (hydra a) this seems unlikely. for hydra a we have shown that massloss from evolved stars produces an insufficient amount of dust to explain the fir luminosity. instead we argue, that dust is produced in connection with star formation in the flow. the detection of fir emission from dust in the icm will provide important constraints for cooling flow models. dedicated iso observations of a sample of cooling flows will (1) learn us about the abundance of dust, (2) give some insight into grain properties (temperatures/sizes) in hot gas, (3) give information on densities and temperatures of the hot gas, (4) test our hypothesis of dust production in cooling flows, (5) maybe supply indirect evidence for lowmass star formation, and (6) show if firemission from dust is a major coolant in cooling flows. *** please notice printed addendum to visitors report *** truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]