Finally, ancestors of Milky Way discovered

Astronomers claimed to have discovered galaxies in the distant universe that are ancestors of spiral galaxies like our Milky Way.

The newly discovered galaxies are quite small -- one-tenth the size and one-twentieth the mass of the Milky Way -- and they also have fewer stars -- only one-fortieth as many as are in the Milky Way, according to the astronomers at the Rutgers and Penn State universities.

While from ground-based telescopes, the galaxies look like individual stars in size, recent images by Hubble Space Telescope reveal them as regions of active star formation.

"Finding these objects and discovering that they are a step in the evolution of our galaxy is akin to finding a key fossil in the path of human evolution," Eric Gawiser of the Rutgers University was quoted by the 'ScienceDaily' as saying.

According to the researchers, these galaxies're fertile breeding grounds for new stars, which burned hot and bright. These stars ionised the hydrogen atoms around them, stripping them of their electrons and causing them to emit a tell-tale sharp band of ultraviolet light, called Lyman alpha.

Moreover, several of these galaxies, sometimes ten or more, pulled together over the ensuing few billion years to form a single spiral galaxy, they found.

"The Hubble Space Telescope has delivered striking images of these early galaxies, with 10 times the resolution of ground-based telescopes. They come in a variety of shapes -- round, oblong, and even somewhat linear -- and we are starting to make precise measurements of their sizes," co-researcher Caryl Gronwall of Penn State University said.

In fact, the astronomers' statistical analyses and computer simulations of how galaxies cluster led them to the conclusion that Lyman alpha emitters are the ancestors of spiral galaxies.

"We knew by our understanding of cosmological theory that spiral galaxies had to evolve from low-mass galaxies such as these. The challenge was to actually find them. We'd seen other early universe galaxies, but they were bigger and destined to evolve into elliptical galaxies, not spirals," Gawiser was quoted as saying.

Courtesy:thehindu.com
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