A map of the major satellite galaxies surrounding the Milky Way. Credit: J. Bullock, M. Geha, R. Powell
Posted on 11/07/2008 4:48:38 PM PST by SunkenCiv
A study of small galaxies circling around the Milky Way found that while they range dramatically in brightness, they all surprisingly pack about the same mass. The work suggests there is a minimum size for galaxies, and it could shed light on mysterious dark matter.
Spinning around the Milky Way are at least 23 pint-sized galaxies, each shining with the light of anywhere from a thousand to a billion suns. Though each of these galaxies is very dim compared to large galaxies like our own, they span a large range in brightness.
Astronomers led by Louis Strigari of the University of California-Irvine studied the movements of individual stars in these satellite galaxies to determine the mass of each galaxy.
"What we found was astonishing, which was that they all had the same mass," said researcher James Bullock, a UC-Irvine astrophysicist. "It's not what we were expecting -- we were really taken off guard."
The finding could help explain the mysterious stuff called dark matter and how it affects the formation of galaxies. Nobody knows what dark matter is, but its presence is revealed by gravity that is not produced by the regular matter that can be seen.
Despite their wide-ranging brightnesses, all of the 23 satellite galaxies around the Milky Way seem to have a central mass of 10 million times that of the sun. And what's more, almost all of that mass seems to be made up of dark matter, with just the tiniest smidgen of visible matter producing stars.
(Excerpt) Read more at space.com ...
A map of the major satellite galaxies surrounding the Milky Way. Credit: J. Bullock, M. Geha, R. Powell
Lots of new science over the past week on Dark Matter. It is starting to look like there really is some mysterious unobservable stuff out there that provides much of the gravity in the universe compared to normal matter.
http://www.universetoday.com/2008/11/06/are-we-close-to-finding-dark-matter/
Time travel is such fun.
thanks NormsRevenge:
Monster galactic cluster seen in deep Universe: European agency
AFP on Yahoo | 8/25/08 | AFP
Posted on 08/25/2008 3:56:31 PM PDT by NormsRevenge
http://www.freerepublic.com/focus/f-chat/2067925/posts
Hey, thanks! Ya wanna take over a ping list? It’s only been driven to and from FreeRepublic about fifty times... :’)
Would this, per chance, have something to do with The Great Square of Pegasus? :-}
Or, for that matter, The Autumn Dipper?
I wish they would name a constellation “The Big Bopper”.
I’ve seen the corners on that thing, and they should call it “The Not-So-Great Square of Pegasus”. ;’)
Didn’t you tell me that last week? Hey, wait a minute...
“I wish they would name a constellation “The Big Bopper”.”
Seldom if ever do I laugh out loud. This was a rare exception. You’re a funny guy.
JPB, I know what you like. ;’)
Their observations are flawed, or there is something about space that they do not understand. A ring of distortion? Rechecking the theories is a mammoth task but...
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