For the first time, a team of British and American astronomers has discovered and studied the effects of what they believe was a collision of two celestial bodies in a newborn star's protoplanetary disk.
The alleged collision left a massive cloud of debris and dust, which happened in the star system HD 166191 (constellation Sagittarius) at a distance of 329 light-years from Earth.
Since 2015, the Spitzer Space Telescope has continuously observed this star and its protoplanetary disk. In mid-2018, regular infrared light monitoring indicated that the star had become much brighter.
Researchers unveiled the details of the study, "A Star-Sized Impact-Produced Dust Clump in the Terrestrial Zone of the HD 166191 System," in The Astrophysical Journal last week.
This illustration shows what a debris cloud around the young star called HD 166191 might look like up close. Astronomers using NASA's now-retired Spitzer Space Telescope saw a debris cloud briefly block the light from that star.
Giant Debris Cloud Found in Space After 2 Objects Collide
The evidence of collision was first discovered in 2018, News9Live said. The researchers found a brightening in the system, indicating an increase in the material surrounding the host star and light from HD 166191 being blocked by the elongated and three-times-the-size-of-the-star debris cloud.
A decrease in the star's brightness when the cloud passed in front of it, in relation to the Earth, known as a transit, was used to discover the debris cloud. Exoplanets are discovered using a similar method.
Over the next several months, the cloud got larger. Still, it also became more transparent, indicating that the debris was spreading through the system. The debris cloud vanished by 2019, yet the system had twice as much dust as before the incident.
NASA Spitzer Space Telescope Finds Post-Collision Activity
The brightness of the HD 166191 increased in mid-2018, indicating activity. Spitzer spotted a debris cloud as it traveled in front of the star, using undetectable infrared light to human sight.
CNN said the images, which ground-based telescopes captured in visible light, matched the observation that showed the cloud's size, form, and rate of evolution.
A similar event had been observed by ground-based telescopes some 142 days before when Spitzer's data were missing.
George Rieke, study co-author and a Regents Professor of Astronomy at UArizona, said in a statement: "There is no substitute for being an eyewitness to an event.
He added: "All the cases reported to date from Spitzer have been unresolved, with only theoretical hypotheses about what the actual event and debris cloud might have looked like."
Spitzer's previous attempts to observe collisions around young stars yielded little results.
As the researchers continued to observe, the debris cloud grew more extensive and transparent as the dust spread swiftly.
In 2019, the cloud was no longer visible. In comparison to Spitzer's findings previous to the impact, there was twice as much dust in the system.
Other infrared observatories are still monitoring the star, and the James Webb Space Telescope, which was recently deployed, is expected to make more observations of these types of collisions.
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