Quote:
Originally Posted by ChrisM
Robert, that NIR image is very revealing with much more detail evident.
Thanks, Chris
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The background light is better able to get through the dust (both the general 'diffuse' screen of dust within a spiral galaxy, and also the individual dark nebulae in a galaxy) in infrared detection. At 2 micrometers (2000 nanometers), extinction is only about 1/9 that which you get when you image at 500nm (blue visible light). However, imaging longward of 1 micrometer requires specialized CCDs.
Also, the O and B -type stars (luminous & young stars which recently formed) that dominate the appearance of the rather chaotically distributed clumps in the spiral arms, are much less prominent when imaging in the infrared.
Thus, Infrared images of galaxies remove much of the confusion that results from a heavy distribution of chaotic dust clouds and a rather chaotic distribution of very luminous stars.
Some of our members have had success, imaging in the very-near infrared at 700nm to 1000 nm (which is the longest wave that standard CCDs can detect) with objects in which there is only a relatively modest amount of dust extinction of the background light.
There is a sense in which the dust and the very luminous stars in spiral galaxies are "sort of like icing on a cake"; in that a chaotic distribution of Dust Clouds and bright eye-catching Stellar Clumps does not have to mean that a galaxy is seriously disturbed or distorted; the underlying mass distribution of a galaxy, as shown in infrared imaging, can still be totally regular and symmetric!!
cheers,
Bad Galaxy Man