The Little Lion galaxy (also called Leoncino) lying 30 million light-years from Earth may shed light on the nature of the Big Bang. The galaxy is a blast from the distant past of the visible universe.
Leoncino, a faint blue family of stars, was found to contain the lowest concentration of heavy elements ever found within a family of stars. The ratio of metals in the galaxy was found to be 29 percent below the previous record holder, discovered in 2005.
After the universe cooled enough following the Big Bang for matter to form, everything that existed consisted of roughly three-quarters hydrogen, one-quarter helium, and trace quantities of lithium. Therefore, early galaxies were composed of just these three lightest elements, a situation seen today (or rather, 30 million years ago) in the Little Lion.
"Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang. There are relatively few ways to explore conditions at the birth of the universe, but low-metal galaxies are among the most promising," John Salzer of Indiana University Bloomington said.
Astronomers refer to any element other than hydrogen or helium as a metal. Finding a galaxy poor in metals provides researchers with an opportunity to study how the earliest galaxies may have behaved billions of years in the past.
All of these metals are produced in stars, both through nuclear fusion and in the dramatic deaths of the most massive stellar bodies during supernova explosions. Our own Milky Way galaxy, ripe with the birth, life, and deaths of stars, is rich in heavy elements. Because of this, astronomers are forced to look far from our own family of stars to find galaxies lacking in metals.
Unlike the Milky Way, which contains hundreds of billions of stars, Leoncino is composed of just a few million stars, stretching a mere 1,000 light-years from one side to another.
Measurement of the metal concentration in the galaxy AGC 198691 was completed through spectroscopy. This process involves breaking light from a distant object into a spectrum of different colors. Changes in the amount of light seen at various wavelengths allow astronomers to deduce which elements exist within the distant body.
Analysis of the metal-poor galaxy of Leoncino is published in The Astrophysical Journal.