dust grains play an important role in determining the cooling, the thermal structure, and the abundance of various refractory elements in fast astrophysical shocks (see review by dwek & arendt 1992). equally important is their destruction, which recycles condensible elements from the solid back to the gaseous phase of the interstellar medium (ism). on a galactic scale, grain destruction regulates the depletions of various refractory elements in the interstellar medium and on a local scale, it affects the ionization structure of the shock, as well as the infrared (ir), the ultraviolet (uv), and the x-ray signature of the shocked gas. there is, however, only circumstantial evidence for the destruction of grains in fast shocks, mostly inferred from iras observations of young supernova remnants. sputtering changes the initial grain size distribution, depleting the population of small grains. these small dust particles with sizes below 0.03 microns are stochastically heated, undergo temperature fluctuations, and radiate an excess of near infrared emission (lamda<30 um) over that expected for grains in thermal equilibrium. this near infrared excess is a measure of the abundance of small grains, and therefore a powerful diagnostic for the amount of destruction the grains concurred in the shock. the iso satellite offers unique capabilities for obtaining the short wavelength emission from stochastically-heated dust in snrs. we propose to use isophot to observe emission from dust both inside and outside several snr shock fronts over a very broad range of wavelengths.
Instrument
PHT17 , PHT18 , PHT19 , PHT37 , PHT38 , PHT39
Temporal Coverage
1996-08-11T01:36:53Z/1997-01-25T09:26:55Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
