The most comprehensive plans require luck, even in space.
In October 2022, james webb space telescope Seen as (JWST or Webb) Cariclo, a small ringed asteroid obscured the star. This event, called an occultation, was a first for Webb. At the end of the month, Webb turned to his Chariklo again and scored another victory. Astronomers analyzing the telescope data have found for the first time clear signs of the previously hinted water ice. These observations will guide astronomers to better understand the nature and behavior of small bodies outside our solar system.
But two feats almost never happened.
Related: Asteroid Chariklo Has Rings: Images of Space Rock Weirdness (Gallery)
Although the largest of its kind, Chariklo is too small and too far away to take a direct photo, even with a powerful Webb. Instead, astronomers decided to study it through occultations. This is an indirect but powerful way to study small objects like Chariklo. But the team didn’t know if the star would be in Webb’s field of view, or when, without it, an occultation wouldn’t occur.This made Chariklo part of the web chance target (opens in new tab) Program: If an asteroid happens to cross in front of the star, this program will allow astronomers to temporarily interrupt their telescope schedules to observe the event.
The team calculated only a 50% chance that Webb would find a star bright enough for an interesting object like Chariklo to cross in front of it. After its launch in 2021, Webb made regular orbit corrections and remained stable in a space parking lot, while the team predicted and corrected a list of possible occultations. . Late last year, astronomers ended up on that 50% advantage when they discovered “by amazing luck” that her Chariklo was on an orbit that obscured a star that came into Webb’s view.
“This was the first stellar occultation attempted on the web,” the team wrote to NASA. statement (opens in new tab) It was published on Wednesday (January 25th). “Major efforts have been made to identify and improve our predictions for this anomalous event.”
On October 18, 2022, Chariklo and its two ring systems crossed in front of the star. Web’s near-infrared camera (NIRCam), astronomers monitored the brightness of the star for an hour. The resulting data showed his two dips in the star’s brightness, as expected. When the eclipse began, when the asteroid ring first hid the star and when the last ring enveloped the eclipse.
“Shadows produced by Chariklo’s rings have been clearly detected,” the team said in a statement.
read more: How it works in pictures from the James Webb Space Telescope
Chariklo-like objects are called centaur, thanks to its hybrid nature. (Centaurs are mythical horse-human hybrids.) They look like asteroids, but behave like comets — complete with visible tailtheir home, unstable orbit between Jupiter and Neptune, hosts thousands of centaurs of various shapes and sizes. They are interesting, but their small size and very long range make them difficult to study. Even the largest centaur, Chariklo, is small at only 160 miles (250 km) in diameter, and he is 2 billion miles (3.2 billion km) away from us. didn’t understand much. Also, Past research It had suggested that there was water ice somewhere in Chariklo’s system, but had yet to conclusively detect it.
In this latest study, astronomers point Webb back at Chariklo. This time, they used the telescope’s Near-Infrared Spectrometer (NIRSpec) instrument to measure sunlight reflected by Chariklo and its two rings. The resulting spectrum showed her three absorption bands of water ice, giving the first clear indication of crystalline ice.
The presence of crystalline ice likely indicates that Chariklo is undergoing constant bombardment, said Dean Hines, an astronomer at the Space Telescope Science Institute in Maryland. In a NASA statement, Hines said, “Since high-energy particles change the ice from a crystalline state to an amorphous state, the detection of crystalline ice will either cause the Chariklo system to expose the original material or trigger the crystallization process. It indicates that it is experiencing continuous micro-collisions.
read more: Rise of the Centaurs: NASA’s Eye Includes Mission to Weird Asteroid-Comet Hybrid
Astronomers have moved one step closer to studying the Chariklo system, but there are still many unknowns about the centaurs. and the data for the two rings is difficult to distinguish.
For example, astronomers have found the first clear signs of crystalline water ice, but they still don’t know where the ice resides in the asteroid system. In the coming months, researchers hope to use Webb’s high sensitivity to delve into individual features of Chariklo and its two rings, said Pablo Santos Sanz. statement.
“we hope [to] We’ll gain insight into why this tiny object has rings, and perhaps detect new faint rings,” Santos-Sanz said.
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