The supermassive black hole at the centre of our galaxy, the Milky Way, is always up to something unusual. Now, astronomers have spotted strange new objects close by but they aren’t quite sure what they are.
Using 13 years’ worth of data from the W.M. Keck Observatory in Hawaii, astronomers were able to identify a new class of objects extremely close to the black hole, Sagittarius A*. According to a study published Wednesday in the journal Nature, the six objects, named G1 through G6, appear to be interacting with the black hole.
According to Andrea Ghez, these objects look like gas and behave like stars. Some astronomers believe the elongated blobs are gas clouds, several times the mass of the Earth. Others think they seem more like small stars covered in dust since they can closely orbit the black hole’s edge without being destroyed by its pull.
Typically, the objects appear compact, but as they near the black hole during their orbits which can last from 100 to 1,000 years they stretch out.
The objects’ behaviours are confusing: It’s not clear if they’re gas or stars. But the study’s authors now believe they may be an unusual hybrid of both.
The first two G objects were found in 2005 and 2012 by Ghez’s research group. After G2 closely approached the black hole in 2014, scientists believed it was likely two stars that had merged into a much larger star, covered in “unusually thick” gas and dust.
“It went from being a pretty innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it’s getting more compact again,” Ghez said.
While the outer shell was dramatically stretched, the inner dust was not, indicating the presence of a stellar object inside G2, lead author Anna Ciurlo said. Sagittarius A* should have ripped G2 to shreds, but instead, the object just passed right by it, prompting scientists to reconsider its classification.
In 2014, Ghez said that G2 survived and continues happily on its orbit; a gas cloud would not do that. Now, the team has discovered G3, G4, G5, and G6. The new objects have completely different orbits than the first two, but they prove they aren’t as rare as once believed, creating an entirely new class of cosmic phenomena.
According to the team, there may be even more unusual objects in this new class, but more analysis is needed. The said this research could explain the chaos that is happening in the majority of galaxies.