If today's big news announcement from the American Astronomical Society (AAS) meeting in Washington D.C. needed a theme song, I'd borrow lyrics from "Kansas City" (from the musical "Oklahoma") i.e. "They've gone about as fur as they c'n go!"
Following the installation of Hubble's new super-panchromatic top resolution camera in May 2009, astronomers quickly used it to take the deepest-ever pictures of the universe.
Like proud parents, astronomers in an AAS press conference showed off these "baby pictures" of small blue blobby galaxies that existed when the universe was only 600 million years old.
These young star clusters are a fraction the size of our full-grown Milky Way. They are described as the "seeds" of galaxies that, under the relentless pull of gravity, merged over billions of years to assemble basically two types of galaxies: pinwheel spirals and bulbous ellipticals.
The intermediate stages of galaxy assembly appear clearly in the same Hubble views. An exotic zoo of odd shapes nicknamed "train wrecks" and "tadpoles" chronicle galaxies pulling their act together.
This is as far as Hubble's present sensitivity will take it. Astronomers are eagerly following the assembly of the larger James Webb Space Telescope scheduled for launch in 2014. The new pictures assure astronomers that Webb will have a lot to go hunting for in the first 500 million years of galaxy birth. We'll go from seeing toddler to infant galaxies.
This feat is amazing considering that when Hubble was launched 20 years ago, the biggest ground-based telescopes could only see normal galaxies out to about halfway across the universe.
In fact in 1985 a committee of top astronomers planning to use Hubble concluded that devoting 200 orbits to a "deep exposure" of the universe would be fruitless. Extrapolating from the known universe of the time, they assumed that the geometry of space at great distances would spread out the light of normal galaxies, making them too diffuse to be seen by Hubble. Fortunately nature cooperated. Early evolving galaxies are more compact and therefore concentrate their light into a smaller area.
Now, as exciting as this is intellectually, it's hard to get goose bumps when looking at blobs that existed far away and long ago.
But, coming full circle in the same press conference, astronomers from NASA's Spitzer Space Telescope unveiled an infrared portrait of the Small Magellanic Cloud (SMC) that lies 65,000 times closer that the farthest seen Hubble galaxies. Only a small fraction the size of the Milky Way, the SMC is a close-up example of what early galaxy toddlers looked like.
The tiny irregular galaxy is ablaze with star formation. The gravitational pull from our Milky Way jump started this galaxy, which has been hanging around in the Local Group of galaxies for the past 13 billion years. The irregular galaxy's flyby of the Milky Way triggered a firestorm of star formation by compressing hydrogen gas.
The SMC can be seen clearly only from southern latitudes. It is so large and diffuse that STS-125 astronaut John Grunsfeld admitted in the AAS press conference that he first mistook it for a grease smudge on the space shuttle orbiter window. He was on the flight deck star-watching with fellow Hubble repairman Mike Massimino.
"I went to wipe off the window and realized I was looking at a galaxy," he said.
Tags: Hubble Telescope, Stars, Universe
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