Friday, September 07, 2007

Star Geek: The Original Series

One of the enduring mysteries for astronomers had been the process by which galaxies form. One common notion had been a top-down arrangement in which enormous clouds of primordial gas gradually coalesced under their own gravity. Another idea has been a "building block" notion under which groups of small galaxies merge to form larger ones. Now that second idea has new support.
Astronomers have found nine of the faintest, tiniest and most compact galaxies ever seen.

The little objects are hundreds to thousands of times smaller and vastly younger than our Milky Way....

"These are among the lowest mass galaxies ever directly observed in the early universe," said Nor Pirzkal of the Space Telescope Science Institute in Baltimore, Md.

Pirzkal said their petite mass, observed by the Hubble Space Telescope and confirmed by the Spitzer Space Telescope, shows these galaxies are some of the smallest building blocks of the universe, aside from stars themselves.
These tiny galaxies appear to have been formed when the universe was only 1 billion years and consist of hot blue stars only a few million years old, still in their youth. (The brightest, hottest, stars use up their nuclear fuel the quickest and thus have the shortest lifespans, about 10-20 million years. A typical yellow star like our Sun will go for about 10 billion years.)
The development of three of the galaxies appears to be slightly disrupted; rather than taking on a rounded-blob shape typical of the youngest galaxies, they're stretched into tadpole-like forms. Astronomers think it may signal their first fusion with neighboring galaxies to form larger, cohesive structures.
And maybe, maybe, astonomers are a step closer to knowing how things got to be the way they are.

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