Object X7 is a dust cloud ejected during the collision of two stars.

For two decades, scientists have observed a tall object called X7 near the supermassive black hole at the center of the Milky Way and wondered what it was. Removed from a larger structure nearby? Was its unusual shape the result of stellar winds or was it shaped by particle jets from the black hole?

Now, after examining the evolution of X7 based on 20 years of data collected by the Galactic Center Orbit Initiative, astronomers from the UCLA Galactic Center Group and Keck Observatory suggest that there may be a cloud of dust and gas ejected during X7’s evolution. two stars collided

They reported that X7 elongated over time and flexed when the black hole brought it closer and exerted a tidal force on the cloud. They expect X7 to disintegrate over the next few decades and the gas and dust that composes it will eventually be drawn into a black hole called Sagittarius A* or Sgr A*.

“No other object in this region has shown such extreme evolution,” said Anna Ciurlo, a research fellow at the University of California, Los Angeles (UCLA) and lead author of the paper. “It was originally comet-shaped, and people thought it might have gotten that shape from the stellar wind or particle jets from the black hole. But after 20 years of following it, we found it to be even longer. Something must have set this cloud in a certain way in its unique way.”

X7 has a mass of about 50 Earth masses and orbits Sgr A* every 170 years.

But that may never happen. Based on its trajectory, the team estimates that X7 will make its closest approach to Sagittarius A* around 2036 and then disappear, possibly approaching Sagittarius A*.

“We expect strong tidal forces from the galactic black hole will eventually tear X7 apart before it even completes an orbit,” said co-author Mark Morris, professor of physics and astronomy at UCLA.

Tidal forces are the gravitational force that causes an object approaching a black hole to stretch; The side of the object closest to the black hole is pulled much stronger than the opposite end. X7 exhibits the same characteristics as other strange dusty objects orbiting Sgr A*. These so-called G-objects look like gas but behave like stars. But the X7’s shape and speed have changed more dramatically than the G objects: As it accelerates into the black hole, the X7 is moving fast, reaching speeds of up to about 700 miles per second.

“It’s fascinating to observe the significant changes in the shape and dynamics of X7 in such detail over a relatively short period of time, as the gravitational forces of the supermassive black hole at the center of the Milky Way act on this object,” Randy said. Campbell, co-author. The statement states that he is the head of article and science operations at the Keck Observatory.

While the origin of X7 is still a matter of debate, findings suggest that it was formed after the collision of two stars.

“One possibility is that the gas and dust of X7 ejected when the two stars merged,” said Ciurlo. “In the process, the merging star is hiding inside a shell of dust and gas that might fit the description of G objects. And the ejected gas may have created X7-like objects.”

According to Ciurlo, merging of two stars is very common, especially when near black holes.

“It’s a very complex process: the stars orbit each other, approach, merge, and the new star is hidden in a cloud of dust and gas,” he said. “X7 could be dust and gas from a merged star that is still out there.”

The resulting data is the first assessment of X7’s moderately elliptical orbit and the most reliable analysis to date of notable changes in appearance, shape and behavior. The research team will continue to use the Keck Observatory to observe X7’s dramatic changes as the black hole’s gravity tears it apart.

“It’s a privilege to be able to study the extreme environment at the center of our galaxy,” Campbell said in a statement. Said. “This research can only be done using Kek’s extraordinary abilities, and on a special and respected Maunakea, with respect and honor to the mahogany.”