Pull-out: “Peekaboo” Dwarf Galaxy HIPASS J1131–31

NASA's Hubble Space Telescope captured a detailed image of the tiny galaxy HIPASS J1131–31, nicknamed the "Peekaboo Galaxy," despite its proximity to a bright foreground star. In addition to Hubble imagery, astronomers used the South African Large Telescope (SALT) to collect detailed spectroscopic data on the galaxy's stars, which show it to be one of the least chemically enriched galaxies ever discovered in the local universe.

Typically, generations of stars produce more—and more complex—chemical elements (which astronomers call "metals") over cosmic time. At the dawn of the universe, 13.8 billion years ago, hydrogen and helium were the only abundant elements. Early galaxies that were made up of some of the first generations of stars had not had time to build up much chemical complexity. Evolved galaxies like our own Milky Way have stars that are many billions of years old and are metal-rich, including all the elements that make life on Earth possible. The stars of the Peekaboo Galaxy, however, appear to be only a few billion years old at most. Why, and how, the Peekaboo Galaxy delayed star-formation for so many billions of years is a question that astronomers will continue to investigate.