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Looking for mini galaxies

When we think of galaxies, we picture vast whirling wheels of stars and dust hundreds of light years in diameter. But space is big enough to challenge our most cherished preconceptions.

NASA's Hubble and Spitzer space telescopes have joined forces to discover nine of the tiniest galaxies ever observed in deep space. The galaxies appear to be a thousand times smaller than our own Milky Way galaxy.

Astronomers have long accepted the fact that small galaxies might exist, but they had never observed one until recently.

"These are among the lowest mass galaxies ever directly observed in the early universe" according to Nor Pirzkal of the Space Telescope Science Institute in Maryland during an interview with SPX. The conventional model for galaxy evolution predicts that small galaxies in the early universe evolved into the massive galaxies of today by coalescing. These nine Lego-like "building block" galaxies initially detected by Hubble likely contributed to the construction of the universe as we know it.

Unlike our big, lumbering Milky Way, these nine mini galaxies are leaner and far younger.

Observing the galaxies is just like gazing through the lens of an optical time machinethese young galaxies formed just one billion years after the Big Bang. And embedded within the galaxies are stunning, blue-sapphire stars. These strange stars, not seen in our end of the (older) universe are a mere million years old. They are, in fact, furiously converting the chemical elements of the Big Bang into heavier elements.

The stars have probably not yet begun to pollute the surrounding space with elemental products forged within their cores, according to Pirzkal. What we see is the pristine space of a primordial stellar laboratory.

"While blue light seen by Hubble shows the presence of young stars, it is the absence of infrared light in the sensitive Spitzer images that was conclusive in showing that these are truly young galaxies without an earlier generation of stars," Sangeeta Malhotra of Arizona State University said in the SPX interview.

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