Astronomers have discovered a cloud mass that is about the size of a star, a distance of 330 light-years. Your cause? A huge crash between the two exoplanets was building.
We know this because astronomers have analyzed the infrared light of the said dust cloud, as well as changes in the light of the host star, which are occasionally extinguished by circulating debris. With this data, we now know the size of the objects involved, and other important details about the collision.
This may provide insight into the structure of our Solar System – and perhaps even illuminate stars with unusual fading patterns, such as KIC 8462852 or Boyajian’s Star, by providing additional information on how rapidly clouds of debris disintegrate.
“For the first time,” said astronomer Everett Schlawin of the University of Arizona’s Steward Observatory, “we imagined both infrared light dust and hardness caused by dust as the cloud passed in front of a star.”
The star in question is the baby ickle, just 10 million years old, named HD 166191. Because of its new design, it is still surrounded by a story, which has been left since it was established.
The stars form a tight knot in a gas cloud that falls under its own weight; spinning, the star grows by expanding the material from the surrounding cloud, as the latter arranges it into a star-bearing disc, like water flowing down a river.
Once the star has finished building, anything left on the disk can continue to form other elements of the planetary system. Lumps of matter stick together, first attracting electrostatic attraction, then gravity.
As you can imagine, this is a dirty process with a lot of collisions. Finally, enough material clings together to form, first the seeds of a planet, or planetesimal, and finally the planet.
Conflicts between bodies can direct the process. Our Moon is thought to have formed when another planetary body hit the Earth during the Solar System youth, for example. But it is not said that all collisions will leave survivors.
Led by astronomer Kate Su of the Steward Observatory, a team of researchers used the now-retired Spitzer Space Telescope to make infrared viewing of HD 166191. In addition, starlight absorbed and retrieved dust shines brightly in infrared.
Between 2015 and 2019, researchers collected 126 sets of data from a star, focusing directly on the surrounding dust clouds that may be the result of a collision.
In 2018, the signal they were looking for emerged: infrared light, which increases the amount of dust, and fading, indicating that starlight was blocked. The same blurring event was taken by a telescope based on light waves – and the same blurring 142 days earlier, during the gap in Spitzer’s vision.
Frequent transport data has confirmed it: The signal is made up of two planets colliding and releasing dust everywhere. Previous observations of the ground-based telescope have increased the orbital time to 142 days, giving the orbital distance from a star of 0.62 star units. That is the distance the rocky planets are expected to form.
Having data from multiple transports also allowed the group to see the appearance of the cloud. It changes rapidly from the first to the second, exits the balloon, grows wider and less visible and longer, covering an area at least three times larger than the star.
But Spitzer’s data suggests that only a small portion of the cloud passed between us and the star. That suggests that the literal cloud was, in fact, massive, probably hundreds of times larger than the star.
To produce such dust, the team calculated that the collision had to be between two bodies the size of a small planet, about 250 to 600 miles (about 250 to 470 miles) wide.
The first collision would cause so much heat that some material evaporated; the remaining part would fly into fragments that continue to squirm and collide, along with other nearby rocks, creating more dust.
By the time the third trip is due to turn around, there is very little trace left of the real cloud. However, the starry heavens had twice as much dust as they had before the collision. This suggests that debris from the collision dispersed rapidly across the protoplanetary disk around the star.
This not only suggests that round clouds of dust may be unsuitable for defining obscure stars in an unusual way, but it may also help to clarify the processes leading to the formation of a complete planetary system, including ours.
“By looking at the dusty disks around the young stars, we can look back in time and see the processes that may be building our Solar System,” said Su.
“By studying the effects of collisions on these systems, we can also get a better idea of the rocky planets that appear to revolve around other stars.”
The team will continue to monitor HD 166191 to see if it can detect some interesting changes in its dusty environment.