The most distant star ever observed has been spotted, and its light comes from across two-thirds of the universe. That puts the star 9 billion light-years away.
Patrick Kelly of the University of California, Berkeley and colleagues found the star in Hubble Space Telescope images of the galaxy cluster MACS J1149. In April and May 2016, Kelly’s team saw a mysteriously fluctuating point of light in the galaxy cluster’s vicinity.
Follow-up images and analyses, reported June 30 at arXiv.org, showed that the 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.
The team calculated how much the star’s light was stretched by its journey, a clue to its distance. Since the universe is 13.8 billion years old, and looking farther into the universe is the same as looking backward in time, 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.