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Since its discovery in 1927, Centaur 29P/Schwassmann-Wachmann 1 has baffled scientists with its highly active and quasi-periodical outbursts, which vary in intensity every six to eight weeks. A closer look at the mysterious icy body revealed three jets of hot gas gushing out of it, suggesting that it’s made of distinctly different parts from various objects.
Using the Webb space telescope’s near-infrared spectrograph instrument, a team of scientists mapped the gasses spewing out of Centaur 29P. Webb’s imaging and spectral data revealed never-before seen features: two jets of carbon dioxide and a new jet of carbon monoxide pointed toward the Sun. The new discovery suggests a surprising origin story for the centaur, and provides scientists with new insight regarding the formation of the solar system. The findings are detailed in a recent study published in Nature.
“The fact that Centaur 29P has such dramatic differences in the abundance of [carbon monoxide] and [carbon dioxide] across its surface suggests that 29P may be made of several pieces,” Geronimo Villanueva, co-author of the study at NASA Goddard, said in a statement. “Maybe two pieces coalesced together and made this centaur, which is a mixture between very different bodies that underwent separate formation pathways. It challenges our ideas about how primordial objects are created and stored in the Kuiper Belt.”
NASA, ESA, CSA, L. Hustak (STScI), S. Faggi (NASA-GSFC, American University) Centaurs are funny little objects. They’re not quite comets nor are they asteroids, and their dual nature is the clear inspiration behind the name. The icy objects used to orbit the Sun from beyond Neptune, but subtle gravitational influences of the giant planets have gradually shifted their orbits. Centaurs are now found between Jupiter and Neptune, but they still share characteristics with both Trans-Neptunian objects (i.e. objects farther away than the orbit of Neptune) and short-period comets, which are altered by their close encounters with the Sun.
“Centaurs can be considered as some of the leftovers of our planetary system’s formation. Because they are stored at very cold temperatures, they preserve information about volatiles in the early stages of the solar system,” Sara Faggi, a researcher at NASA’s Goddard Space Flight Center, and lead author of the study, said in a statement. “Webb really opened the door to a resolution and sensitivity that was impressive to us—when we saw the data for the first time, we were excited. We had never seen anything like this.”
Based on the data, the team behind the discovery created a model of the jets, which suggested that they were spewing out of different regions on the centaur’s nucleus. The angles at which the jets are being emitted also suggest that the nucleus may be an aggregate of distinct objects with different compositions.
The scientists, however, are still not sure what may be causing Centaur 29P’s dramatic bursts of brightness and the mechanism that drives its jets of hot gasses. The jets of comets, for example, are driven by the outgassing of water, but centaurs are too cold for water ice to change its form.
In order to get a better sense of what drives the jets, the researchers want more time with the centaur. “We only had time to look at this object once, like a snapshot in time,” Adam McKay, a researcher at Appalachian State University, and co-author of the study, said in a statement. “I’d like to go back and look at Centaur 29P over a much longer period of time.”
More: Beyond the Planets: The Quirky Underdogs of the Solar System
