G, this is an interesting finding…

The first G object was discovered in 2005 and was labeled G1. Seven years later, a second body was found, and given the moniker G2. The four newly-discovered objects are named G3 through G6. While G1 and G2 have the orbits similar to each other, the newly-found bodies follow significantly different paths around the center of the Milky Way.

“At the time of closest approach, G2 had a really strange signature. We had seen it before, but it didn’t look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. 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,” said Andrea Ghez, professor of astrophysics at UCLA and director of the UCLA Galactic Center Group.

A rendering of G objects being stretched by the supermassive black hole at the center of the Milky Way (center). Image credit: Jack Ciurlo/UCLA

Following the discovery of the first pair of these bodies, Ghez and her team studied the region near the center of our galaxy, including the examination of 13 years of data from the Keck Observatory on Maunakea in Hawaii.

“No broad consensus has yet been reached concerning their nature: the G objects show the characteristics of gas and dust clouds but display the dynamical properties of stellar-mass objects,” researchers report in an article detailing their study, published in Nature.

Ghez believes these G objects were once pairs of binary stars which merged into single objects due to the extreme gravitational forces near the supermassive black hole. Such a process would take roughly one million years to complete, research suggests.

G objects and stars surrounding the supermassive black hole near the center of our galaxy. Image credit: Animated .gif created by The Cosmic Companion from a video produced by the UCLA Galactic Center Group.

Gas within the G2 object was significantly stretched by gravity from Sgr A*, while dust within the body did not expand toward the black hole to nearly the same degree. This suggests a stellar-sized mass withing G2 is keeping the body largely intact.

“One of the things that has gotten everyone excited about the G objects is that the stuff that gets pulled off of them by tidal forces as they sweep by the central black hole must inevitably fall into the black hole. When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon,” stated Mark Morris, UCLA professor of physics and astronomy.