Let’s talk about the elephant in the room, or rather the supermassive black hole at the center of our Milky Way galaxy. We know it’s there, and it clearly influences the behavior of the objects around it. Now, scientists think it may also be triggering the creation of weird structures that look like clouds of dust but act like stars.
That’s according to unpublished research presented at the annual conference of the American Astronomical Society this week. The team behind it believes they have found three additions to a class of strange space things known as G-objects, of which two had previously been identified. They also have an idea of how the oddballs might have formed.
“They’re weird because they are not gas nebulae, they’re not stars, so we think they’re something in the middle, a stellar object surrounded by gas and dust,” Anna Ciurlo, an astronomer at the University of California Los Angeles, told Newsweek, “like a star that’s been puffed up.” The first two such objects caught astronomers’ eyes in 2004 and 2012.
Scientists knew they must be surrounded by dust because they produce very red light and look cool (thermally). In their data, there’s no sign of a star. But the first two G-objects have snuck awfully close to the supermassive black hole at the galaxy’s core without being torn to bits, which means they must be much denser than a cloud of dust. That’s where the idea of a star surrounded by gas comes from.
To Ciurlo and her colleagues, the vicinity of the supermassive black hole also suggested a mechanism that could create the strange G-objects. Previous research suggests that a nearby black hole encourages closely-paired stars to collide more quickly than they would without its influence. Now, the team thinks that those collisions may create G-objects.
The additional identifications suggest G-objects might be a little more common than scientists had thought, which could solve a second mystery about the galactic center, the large number of young stars found there. The two colliding stars, while old themselves, would create a new star, quite large, that would look astronomically like a young star. For a while, that star would be masked by the dust, but the team thinks that star would slowly lose its veil, becoming just another young star.
The research team was inspired by a collection of 12 years’ worth of observations of the center of the Milky Way galaxy, an incredibly crowded neighborhood. Scientists have done a fair amount of research on the stars in that data set, but the team behind the new research wanted to use the same data to tackle different questions.
“We subtracted out the stars from the data and we wanted to look at just the gas around the supermassive black hole,” Randy Campbell, a technical lead at Keck Observatory in Hawaii, told Newsweek. Then, they used data about the location and velocity of that dust to see what was changing over time—only to have what looked like three more G-objects popped out at them. “It was surprising, but you like to be surprised in science,” Campbell said.
Both Ciurlo and Campbell emphasized that right now their research is preliminary. “It’s still all ongoing analysis, we are not totally sure that is the right interpretation,” Ciurlo said, but the fact that it would explain both G-objects themselves and the strange prevalence of young stars in the center of the galaxy makes it an intriguing approach for her. “It’s pretty tempting as an explanation.”
Campbell added that finding the three new examples will let scientists start focusing instead on trying to support or reject different hypotheses about them. And according to Ciurlo, that process should be fulfilling whether or not their own hypothesis about G-objects holds up. “Whatever they are, even if they’re not binary mergers, they have something interesting to tell.”
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