Astronomers at Indiana University have spotted a small blue galaxy approximately 30 million light-years away from the Earth in the constellation Leo Minor. The team believes that the galaxy, nicknamed Leoncino, contains the lowest amount of metal chemical elements ever seen in a system of stars held together by gravity and could help better understand the conditions present at the birth of the universe.
"Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang," said John Salzer of Indiana University and co-author of 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."
The elemental composition of metal-poor galaxies is close to the composition predicted by current models of the early universe. However, these galaxies are typically far away from the Earth, as our own Milky Way galaxy contains a high level of heavier elements due to the creation of these elements by stars and distribution into our galaxy by supernovae.
"Low metal abundance is essentially a sign that very little stellar activity has taken place compared to most galaxies," said Alec Hirschauer of Indiana University and lead author of the study.
The team determined the abundance of elements in the galaxy using spectroscopic observations to capture the light waves emitted by the system and in turn viewed the light emitted by the galaxy, much in the same way that we observe the rainbow resulting from a prism dispersing sunlight.
In addition to possessing lower amounts of heavier elements, Leoncino is a "dwarf galaxy" that is only around 1,000 light years in diameter and consists of just several million stars compared to the Milky Way's 200 billion to 400 billion stars.
Leoncino also possesses a unique blue color due to the presence of recently formed hot stars. Yet despite this color, it has a very low luminosity - the lowest ever observed in a system of its type.
"We're eager to continue to explore this mysterious galaxy," Salzer said. "Low-metal-abundance galaxies are extremely rare, so we want to learn everything we can."
The findings were published in the May 12 issue of The Astrophysical Journal.
