About 26,000 light-years away, a strange, massive cloud is expanding and contracting under the powerful tidal forces of Sagittarius A*, the supermassive black hole at the center of our star. In just 13 years, astronomers expect this cloud, known as X7, to be torn apart by extreme weather.
But now, according to a paper published this week a The Astrophysical JournalThe destroyed cloud, 3,000 times the distance from Earth to the Sun, gives clues to the strange and extreme conditions around a dark hole 4 million times more massive than the Sun.
What is X7?
When X7 was first spotted in 2007, astronomers described it as a comet-shaped object near the galactic center. X7 is classed as a G object, a cluster of supermassive gas orbiting the supermassive black hole Sagittarius A* (Sgr A*) in the center of the Milky Way that behaves like a cloud of gas when only distant from the black hole to hold. together like the stars as they approach their orbits.
Despite the dramatic comparison, X7 is much larger than any other comet – about 50 times the mass of the entire universe. In the last decade and a half, though, astronomers have been able to watch X7 stretch and move in real time. During this time, X7 is twice as large as it once was – indicating that Sgr A* is stretching it like a bacon. It’s still “very small and light,” said Anna Ciurlo, an assistant researcher at UCLA and lead author of the paper. Translationand “that is why he stood up, because he was weak against the soldiers of the pit.”
A filament like X7 is an extreme object – although it travels at 490 miles per second, its orbit around the black hole at the center of the Milky Way would take 170 years to complete in success (more on that in a moment).
“It was only created a few years ago, and in a few years, it will be destroyed. And a few years ago, even a hundred years, is a limited time on the astronomical scale,” said Ciurlo. “So you’d have to be lucky enough to watch this thing shortly before it was destroyed and after it was created.”
Or at least, she added, “you have to be lucky unless these kinds of things are unrelated.”
Finish your meal, Sgr A*
Just what kind of thing the X7 is and where it came from is still a mystery. When it was first discovered, astronomers thought it might be the result of a jet or wind blown from a nearby star, S0-73. But looking at data from the past 20 years, the team found that the two are not moving in the same direction, and they are not at the same growth rate.
A filament of gas like X7 could have been ejected from a nearby star, or it could have been ejected from a larger system, Ciurlo said, but “it’s going in a slightly different direction, so it’s hard to make out.” think how. [those] will put it in the orbit it is in now.”
Instead, the team suspects X7 is the result of an intrusion between two binary stars. In the extreme atmosphere around the supermassive supermassive, binary stars are common, and so are collisions and mergers between them. If the two stars collide, a long stream of gas and dust will be ejected from their violent collision, which will match the shape and characteristics of X7. This “fits the story we’re telling about the galactic center,” Ciurlo said. “It’s not a sure answer, but this situation is a good fit.”
Although zooming through the center of our galaxy at high speed, X7 will be separated from the Sagittarius A* fleet before it completes its next 170-year cycle. In 2036, the team estimates, X7 will reach its closest approach to a black hole. “We’ve already seen it break up,” Ciurlo said, “and we’ll see it turn into gas and dust, and fade as it decays. We’ll lose it at some point.”
Although X7 is zipping around Sagittarius A* 26,000 light-years away (and its fate was sealed about 25,987 years ago), this is still 794,000 light-years closer to the next deep hole, in the dwarf galaxy Leo. This means astronomers will “be able to observe what’s happening with a gas cloud near a supermassive crater,” Ciurlo said. “You can’t get that anywhere else.”
With the Keck telescopes used to observe it since 2002, JWST is scheduled to observe Sagittarius A* and X7 in the coming months. JWST observes a different spectrum than the Keck Observatory, so, Ciurlo said, “this will give us insight into the structure of the object.” In the meantime, while the X7 is still with us, she said, “we’ll keep watching as long as we can.”
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