NASA's Hubble and Spitzer Space Telescopes have joined forces to discover nine of the smallest, faintest, most compact galaxies ever observed in the distant universe, NASA reported Thursday.
Blazing with the brilliance of millions of stars, each of the newly discovered galaxies is a hundred to a thousand times smaller than our Milky Way Galaxy.
"These are among the lowest mass galaxies ever directly observed in the early universe," says Nor Pirzkal of the Space Telescope Science Institute in Baltimore, Md.
Three of the galaxies appear to be slightly disrupted -- rather than being shaped like rounded blobs, they appear stretched into tadpole-like shapes. This is a sign that they may be interacting and merging with neighboring galaxies to form larger, cohesive structures.
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.
Pirzkal was surprised to find that the galaxies' estimated masses were so small. Hubble's cousin observatory, NASA's Spitzer Telescope was called upon to make precise determinations of their masses. The Spitzer observations confirmed that these galaxies are some of the smallest building blocks of the universe.
These young galaxies offer important new insights into the universe's formative years, just one billion years after the Big Bang. Hubble detected sapphire blue stars residing within the nine pristine galaxies. The youthful stars are just a few million years old and are in the process of turning Big Bang elements (primarily hydrogen and helium) into heavier elements.
"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," says Sangeeta Malhotra of Arizona State University, one of the investigators.
Source: Xinhua
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