the dust content of spiral galaxies is an important, and poorly known, property. optically backlit galaxies offer a direct way to measure the extinction through spiral disks, and give results suggesting that the dust is clumped, which is crucial to the overall effects of dust on the starlight. iso measurements offer the opportunity for a classical test for the degree of clumping, via measurements of the same dust population in emission and in absorption. we propose iso observations at 12,50,100, and 200 microns of the four most appropriate galaxy pairs, in which a smooth early-type galaxy shines through the disk of a reasonably symmetric foreground spiral. as long as the 200-micron band has an important contribution from the mass-dominant part of the dust distribution, we will be able to derive any of several indices of dust clumping, for input to more realistic models of the transfer of stellar radiation within galaxies.
Instrument
CAM01 , PHT32
Temporal Coverage
1996-06-02T14:21:41Z/1996-08-22T20:32:00Z
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.
