NASA's TESS uncovers violent starquakes in a distant red giant

NASA’s TESS space telescope has detected starquakes in a distant red giant. The star sits in the binary system Gaia BH2, first spotted by the European Space Agency’s Gaia probe in 2023. The findings reveal unusual traits that challenge expectations about such stars. The red giant lies roughly 3,800 light-years away in the constellation Centaurus. It completes a full rotation every 398 Earth days, a pace faster than typical for isolated red giants of its age. This rapid spin suggests a violent past, possibly involving a merger with another star or an encounter with the massive star that later became its black hole companion.

TESS recorded oscillations rippling through the star, caused by internal starquakes. These vibrations offer clues about its turbulent history. Despite being about 5 billion years old, the star has an unexpectedly high concentration of heavy elements. This chemical signature, combined with its youthful spin, implies it once gained extra mass from a nearby companion. The discoveries provide new details about the complex lives of binary systems with black holes. The red giant’s fast rotation and unusual chemistry point to past interactions that shaped its evolution. These observations help scientists piece together the histories of such rare cosmic pairings.