Strange objects at the center of the Milky Way

Sometimes they behave like a cloud of gas and then they’ll start behaving again almost like an ordinary star: the so-called “G-objects,” which astronomers describe in an article in the scientific journal Nature, are hard to fit into any single category. Six of these objects have already been identified by researchers. They were all found in the direct vicinity of the center of our Milky Way – orbiting the supermassive black hole, Sagittarius A*.

This point of commonality probably also contributes to their strange behavior. G1 to G6 have orbits that lead them around the black hole once every 100 to 1000 years. Whenever they get close to the black hole, they are stretched like chewing gum by its gravity, and then they apparently contract again as they move farther away.

The researchers believe that these G-objects are former binary systems, that is, systems made of two stars that merged together at some point under the influence of Sagittarius A*. But this merging process isn’t over yet – normally the merger of two stars will take up to a million years. Now, as their dance of unification brings them closer to the black hole, the black holes’ gravity pulls the two components apart. Then, as they move away from the black hole, they find each other again and spin together again due to their mutual forces of attraction.

The known G-objects at the center of our Milky Way (picture: Anna Ciurlo, Tuan Do/UCLA Galactic Center Group)
Artist’s depiction of a G-object. The black hole is located at the center of the picture. (picture: Jack Ciurlo)

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