We never know everything there is to know about a person from the first glance – or anything else, for that matter. And that includes the stars. It takes a lot of time, and a lot of looks with different instruments, to piece together the whole story.

One example is the system Gaia BH2. It consists of two known objects. But there might once have been a third object – a star that was gobbled up.

The system was discovered by Gaia, a space telescope. It revealed two objects: a black hole about nine times as massive as the Sun, and a giant star about 1.2 times the Sun’s mass. They orbit each other once every three and a half years.

Ground-based telescopes revealed the composition of the giant. Its chemistry looked like that of an ancient star.

But observations by TESS, another space telescope, suggested otherwise. The satellite measured “starquakes” on the surface of the giant star. Sound waves bounce around inside the star and back to the surface. So just as an earthquake tells us what’s happening below the surface of Earth, a starquake tells us what’s happening deep inside a star.

The quakes revealed that the star spins faster than expected. That suggests it was spun up by interactions with something else. It might have swallowed debris that encircled the black hole. Or it might have swallowed another star, changing the chemistry at its surface – prematurely “aging” this giant star.

Script by Damond Benningfield