Science and Space

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The youngest galaxy ever seen in the universe

Using Hubble Space Telescope, scientists have measured the age of what may be the youngest galaxy ever seen in the universe. Called I Zwicky 18, it may be as young as 500 million years old. Our Milky Way galaxy by contrast is over 20 times older, or about 12 billion years old.

The baby galaxy managed to remain in an embryonic state as a cold gas cloud of primeval hydrogen and helium for most of the duration of the universe’s evolution. As innumerable galaxies blossomed all over space this late-bloomer did not begin active star formation until some 13 billion years after the Big Bang, and went through a sudden first starburst only some 500 million years ago.

Located only 45 million light-years away I Zwicky 18 might represent the only opportunity for astronomers to study in detail the building blocks from which galaxies are formed. It remains a puzzle why the gas in the dwarf galaxy, in contrast to that in other galaxies, took so long — nearly the age of the universe — to collapse under the influence of gravity to form its first stars.

The finding provides a new insight into how galaxies first formed. The galaxy I Zwicky 18 offers a glimpse of what the early Milky Way may have looked like 13 billion years ago.

Large galaxies such as the Milky Way are thought to grow hierarchically, with smaller galaxies merging into bigger galaxies, like tributaries merging into large rivers. I Zwicky 18 is prototypical of this early population of small dwarf galaxies.

posted by: kyawoo at 11:17 | link | comments (1) |
astronomy

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