Red Giant “Star Songs” Reveal Their Chaotic Pasts
Astronomers have studied two red giants, BH2 and BH3, each orbiting dormant black holes in binary systems Gaia BH2 and Gaia BH3. BH2 shows signs of having consumed its companion star, indicated by its age and rotation, while BH3 is an ancient star defying cosmological expectations by lacking predicted brightness oscillations. These systems are among the closest black hole binaries to Earth, located 3,800 and 1,900 light-years away respectively in the constellations Centaurus and Aquila.