Free Astronomy Magazine March-April 2025

MARCH-APRIL 2025 Hubble tracks down a ‘blue lurker’ among stars by NASA/ESA − Ray Villard T he name “blue lurker” might sound like a villainous charac- ter from a superhero movie. But it is a rare class of star that NASA’s Hubble Space Telescope ex- plored by looking deeply into the open star cluster M67, roughly 2,800 light-years away. Forensics with Hubble data show that the star has had a tumultuous life, mixing with two other stars gravitationally bound together in a remarkable triple-star system. The star has a kinship to so-called “blue stragglers,” which are hotter, brighter, and bluer than expected because they are likely the result of mergers between stars. The blue lurker is spinning much faster than expected, an unusual behavior that led to its identification. Otherwise it looks like a normal Sun-like star. The term “blue” is a bit of a mis- nomer because the star’s color blends in with all the other solar- mass stars in the cluster. Hence it is sort of “lurking” among the com- mon stellar population. The spin rate is evidence that the lurker must have siphoned in material from a