Tiny, faint Leo P may point to additional galaxies hidden in our corner of the cosmos.
In recent years astronomers have extended their view almost to the very edge of the observable universe. With the venerable Hubble Space Telescope researchers have spotted a handful of galaxies so faraway that we see them as they appeared just 400 million years or so after the Big Bang.
But even as astronomers peer ever deeper into the Universe to explore the cosmic frontier, others are finding new realms to explore in our own backyard. Such is the case with Leo P, a dwarf galaxy that astronomers have just discovered in the Milky Way’s vicinity. At a distance of some five million or six million light-years from the Milky Way, Leo P is not quite a next-door neighbor, but on the vast scales of the Universe it counts as a neighbor nonetheless.
Intriguingly, Leo P seems to have kept to itself, rarely if ever interacting with other galaxies. So the discovery, detailed in a series of studies inThe Astronomical Journal1, offers astronomers a rare glimpse at a cosmic object unsullied by disruptive galactic encounters. It also suggests the presence of other small galaxies that await discovery in our corner of the cosmos.
Leo P is one of just a few dozen local galaxies that does not swarm around the Milky Way or its massive sibling Andromeda, each of which has been extensively scanned for companion galaxies in recent years. “There has been a massive increase in the number of these nearby galaxies” around the Milky Way and Andromeda, says astronomer Alan McConnachie of the National Research Council Canada’s Herzberg Institute of Astrophysics, who did not contribute to the new research. “There have really been very, very few discoveries of dwarfs that are sort of sitting out in the middle of nowhere.” Those lonely dwarf galaxies, such as Leo P, are hard to spot because they are faint, distant, and could be found anywhere on the sky.