The most distant star ever observed has been spotted, and its light comes from across two-thirds of the universe. That puts the star a whopping 9 billion light-years away.
Patrick Kelly at the University of California, Berkeley and his colleagues found the star in Hubble Space Telescope images of a galaxy cluster called MACS J1149. In April and May 2016, Kelly and his team saw a mysteriously fluctuating point of light in the galaxy cluster’s vicinity.
Follow-up images and analyses, posted June 30 at arXiv.org, showed that light is probably from a single bright blue star that coincidentally was behind the galaxy cluster, aligned along Hubble’s line of sight. The star is visible because the galaxy cluster’s gravity bent spacetime around the cluster, making it act like a cosmic magnifying glass. This phenomenon, called gravitational lensing, helps astronomers observe objects more distant than telescopes can see on their own.
The team calculated how much the star’s light was stretched by its journey, which was a clue to its extreme distance. Since the universe is 13.8 billion years old, that means this star’s light has crossed 65 percent of the universe to reach us. The previous farthest star observed directly was just 55 million light-years away.