'Starquakes' show young red giant orbiting dormant black hole
Astronomers used starquakes, tiny vibrations inside stars, to study a red giant in Gaia BH2 system that looks chemically ancient despite being about 5-billion-year-old. Analysis of starquakes revealed that the star spins much faster than expected. Its unexpectedly rapid spin, suggests it may have merged with another star or gained material during the formation of its dormant black-hole companion.