Metal-poor galaxy could help test the Big Bang theory

Hubble image of AGC 198691(Credit: NASA; A. Hirschauer & J. Salzer, Indiana University; J. Cannon, Macalester College; and K. McQuinn, University of Texas)

A team of astronomers has discovered a faint blue dwarf galaxy nicknamed Leoncino or the "little lion," that could be used as a tool to test the Big Bang Theory. The little lion is the most metal-poor galaxy ever discovered, meaning that it could act as a time capsule, allowing scientists to glimpse the conditions prevailing soon after the creation of our universe.

Shining blue in the light of a new generation of stars, Leoncino (or AGC 198691) sits roughly 30 million light-years distant from Earth in the constellation Leo Minor. Astronomers were able to determine the galaxy's low metal content by bringing to bear a pair of spectrographs mounted on two Arizona based instruments – the Mayall 4-meter telescope at the Kitt Peak National Observatory, and the Multiple Mirror Telescope, located at the Mount Hopkins summit.

Any element heavier than helium and hydrogen is known as a metal. In metal-rich galaxies heavier elements are created through the lifecycles of generations of stars via a technique known as "stellar processing." A star creates metals through nucleosynthesis, and distributes these elements throughout the galaxy upon going supernova, seeding the next generation of stars in the process.

A metal-poor galaxy is an environment wherein this process has been somehow stunted, leaving it with a chemical make-up similar to that of the early universe. Since our current model of the Big Bang makes fairly detailed predictions regarding the ratio of hydrogen and helium atoms following the creation of the universe, we can use these metal-poor time capsules to test one of mankind's most venerated scientific theories.

"Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang," states John J. Salzer, associate professor of astronomy at Indiana University Bloomington, and co-author of a paper on the study. "There are relatively few ways to explore conditions at the birth of the universe, but low-metal galaxies are among the most promising."

Moving forward, the team hopes to undertake further observations of Leoncino in order to squeeze as much information as possible out of the rare galactic treasure.

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