Astronomers had the opportunity to observe a huge cloud of debris the size of a star from a collision that passed in front of a nearby star and blocked some of its light. This temporary dimming of starlight, known as transits, is often a method used to detect the presence of exoplanets around stars outside our solar system. But this time, the observations revealed evidence of a collision between two celestial bodies potentially the size of giant asteroids or small planets, the scientists said.
A team of astronomers began routinely observing HD 166191, a 10-million-year-old star similar to our Sun located 388 light-years away. In 2015. Astronomically speaking, it’s still a very young star – given that our Sun is 4.6 billion years old. At this age, minor planets usually form around stars. The masses of dust left over from star formation and orbiting around them turn into rocky bodies, unlike asteroids left over from the formation of our solar system. Small planets around other stars can accumulate material and increase in size, eventually becoming planets.
Gas, which is necessary for star formation, spreads over time between the smaller planets – so these objects are more likely to collide with each other.
Debris provides clues to planet formation
The minor planets are too small to be seen with telescopes, but when they collide with each other, the dust clouds are large enough that they can be observed.
Based on the observable data, the researchers initially thought that the debris cloud had become so rectangular that it occupied an area about three times the size of the star – an underestimate. But Spitzer’s infrared observations saw only a small portion of the cloud pass in front of the star, while the entire debris cloud covered an area hundreds of times the size of the star.
To create such a massive cloud, the collision was likely caused by two objects similar in size to Vesta, a giant asteroid roughly 530 kilometers across the size of a dwarf planet. In the main asteroid belt between Mars and Jupiter in our solar system, combined.
When these two celestial bodies collided, they produced enough heat and energy to vaporize some of the debris. Parts of this collision likely smashed into other small objects orbiting HD 166191, contributing to the formation of the dust cloud that Spitzer saw.
Study author Kate Su, a research professor at the University of Arizona’s Steward Observatory, said in a statement. “By learning about the outcome of collisions in these systems, we can also get a better idea of how often rocky planets form around other stars.”
The first eyewitness watching the effects of the collision
In mid-2018, the brightness of HD 166191 increased, indicating activity. Spitzer, who observed infrared light invisible to the human eye, detected a cloud of debris as it moved in front of the star. This observation was compared to that captured in visible light by ground-based telescopes, which revealed the cloud’s size and shape, as well as the speed of its evolution. Ground-based telescopes also experienced a similar event about 142 days ago, during a period when there was a hiatus in Spitzer’s observations.
“For the first time, we captured the infrared glow of dust and the haze that the dust enters as the cloud passes in front of the star,” said study co-author Everett Schlowen, associate professor at the University of Arizona’s Steward Observatory. . So.
“There is no substitute for being an eyewitness to an event,” said study co-author George Rick, professor of astronomy and planetary sciences at Regents University. Steward Observatory at the University of Arizona in a statement. “Not all previously reported cases of Spitzer have been resolved, with only theoretical hypotheses about the shape of the actual event and the debris cloud.”
As the researchers continued their observations, they watched the debris cloud expand and become more transparent as the dust spread rapidly.
The cloud is no longer visible in 2019. However, there was twice the amount of dust in the system compared to Spitzer watches before the collision.
The research team continues to observe the star using other infrared observatories and expects more observations of these types of collisions with the newly launched James Webb Space Telescope.
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