Dark matter, which dominates the halo, makes up the majority of the universe’s mass and is thought to be responsible for its core structure, with its gravity influencing visible matter to come together and form stars and galaxies.
The far outer edge of the halo is a poorly understood region of the Milky Way. These newly identified stars are about half the distance from the Milky Way’s neighboring Andromeda galaxy.
“We can see that the suburbs of the Andromeda halo and the Milky Way halo are indeed extended – and are almost ‘back-to-back,'” Feng said.
The search for life beyond Earth has focused on rocky planets orbiting Earth in what are called “habitable zones” around stars. More than 5,000 planets, called exoplanets, have already been discovered beyond our solar system.
“We don’t know for sure, but about every one of these outer halo stars must be likely to have planets orbiting the Sun and other Sun-like stars in the Milky Way,” said Guha Thakurta.
