Astronomers Discover Oldest Main-Sequence Star Aged 10.2 Billion Years

Astronomers have successfully used the Keck Planet Finder instrument at Hawaii's W.M. Keck Observatory to detect subtle oscillations in the nearby orange-hued star HD 219134, a breakthrough for the field of asteroseismology, which studies stellar vibrations to reveal details about stars' interiors. Unlike previous studies that focused on hotter stars using space telescopes, this research marks the first time such 'stellar songs' have been captured from a cooler star via precise velocity measurements. The team, led by Yaguang Li, determined HD 219134's age to be 10.2 billion years—making it more than twice as old as our Sun and one of the oldest main-sequence stars with an asteroseismically determined age. These findings refine models of stellar aging, revealing that spin-down in such stars appears to stall later in life. This research opens new possibilities for probing stars once thought too quiet to study. The findings have been published in the Astrophysical Journal.