by Ann » Thu May 19, 2011 5:00 am
Beyond wrote:That's one heck-of-a-size difference in those two Galaxies. It looks like the little one is biting off more than it can chew
Well put!
As for NGC 253 itself, it is one of the best-looking galaxies in the sky when you view it through a small telescope. Its nickname, the Silver Dollar Galaxy, tells you how beautiful it looks from afar. But close up, like in this Hubble picture, it is rather messy. There isn't much structure to be seen, but there is a lot of chaotic dust. I checked it with my software, and while its B magnitude is 8.147 ± 0.585, its far infrared magnitude (which is a signature of dust) is 5.632, about two and a half magnitudes brighter than the B light magnitude! That is indeed very dusty as galaxies go. The only nearby galaxy that I can think of which is comparably dusty is M82. Indeed, M82 is even dustier, because it is actually
three and a half magnitudes brighter in the far infrared than in blue light. Most unusual. But M82 is a much smaller galaxy than NGC 253, so the total amount of dust in NGC 253 is much greater.
M82.
There are several interesting similarities between M82 and NGC 253. Both are characterized by an intense starburst close to the center of the galaxy. Both are very dusty. Both have rather small amounts of star formation and rather red colors away from the central region.
The biggest difference between the two galaxies is the amazing twin red outflows of ionized gas from the center of M82, of course!
Ann
[quote="Beyond"]That's one heck-of-a-size difference in those two Galaxies. It looks like the little one is biting off more than it can chew :!: :lol:[/quote]
Well put! :D
As for NGC 253 itself, it is one of the best-looking galaxies in the sky when you view it through a small telescope. Its nickname, the Silver Dollar Galaxy, tells you how beautiful it looks from afar. But close up, like in this Hubble picture, it is rather messy. There isn't much structure to be seen, but there is a lot of chaotic dust. I checked it with my software, and while its B magnitude is 8.147 ± 0.585, its far infrared magnitude (which is a signature of dust) is 5.632, about two and a half magnitudes brighter than the B light magnitude! That is indeed very dusty as galaxies go. The only nearby galaxy that I can think of which is comparably dusty is M82. Indeed, M82 is even dustier, because it is actually [i]three[/i] and a half magnitudes brighter in the far infrared than in blue light. Most unusual. But M82 is a much smaller galaxy than NGC 253, so the total amount of dust in NGC 253 is much greater.
[img2]http://chandra.harvard.edu/photo/2000/m82bh/m82_optical.jpg[/img2]
M82.
There are several interesting similarities between M82 and NGC 253. Both are characterized by an intense starburst close to the center of the galaxy. Both are very dusty. Both have rather small amounts of star formation and rather red colors away from the central region.
The biggest difference between the two galaxies is the amazing twin red outflows of ionized gas from the center of M82, of course!
Ann