There is something really strange at the center of the Milky Way. The vicinity of a supermassive black hole is a pretty weird place to start, but in 2020 astronomers have discovered six objects orbiting Sagittarius A* that are unlike anything else in the galaxy. They’re so strange that they’ve been given an entirely new class – what astronomers call G-objects.

The first two objects, designated G1 and G2, first caught the attention of astronomers about two decades ago, and their orbits and strange natures gradually came together in the following years. With gas and dust emission spectra, they looked like giant gas clouds 100 AU in diameter, stretching longer as they approached the black hole.

But G1 and G2 did not behave like gas clouds.

“These objects look like gas but behave like stars,” said physicist and astronomer Andrea Guez of the University of California, Los Angeles, in 2020.

Guez and colleagues have been studying the galactic center for over 20 years. Based on these data, a team of astronomers led by UCLA astronomer Anna Churlo identified four more such objects: G3, G4, G5, and G6. They are in very different orbits from G1 and G2; Together, the orbital period of G objects is between 170 and 1600 years.

It’s unclear exactly what they are, but Guez believes the big clue is that G2 emerged unscathed from the periapsis, the closest point to its orbiting black hole, in 2014.

“At maximum convergence, the G2 had a really weird signature,” he said.

“We’ve seen this before, but it didn’t seem so strange until we got closer to the black hole and elongated and much of its gas was shattered. Far away from a black hole it was a pretty harmless object, but on closest approach it actually flexed and distorted and lost its outer shell, and now it’s even more so. becomes compact.”

Astronomers believe the answer lies in massive binary stars. For the most part, these twin stars locked in mutual orbit hang out with their friends just for business. Sometimes, however, they can merge with each other to form a massive star, like binary black holes colliding. Source