Although our Solar System is billions of years old, we 麻豆精品 S檝e only recently become better acquainted with one of its more dynamic and captivating inhabitants known as (2060) Chiron.
Chiron belongs to the class of objects that astronomers call 麻豆精品 S淐entaurs. 麻豆精品 S� Centaurs are space objects that orbit the sun between Jupiter and Neptune. They are akin to the mythological creature they borrow their name from in that they are hybrid, possessing characteristics of both asteroids and comets.
Using the James Webb Space Telescope, UCF (FSI) scientists recently led a team that found, for the first time, that Chiron has surface chemistry unlike other centaurs. Its surface has both carbon dioxide and carbon monoxide ice along with carbon dioxide and methane gases in its coma, the cloud-like envelope of dust and gas surrounding it.
The researchers 麻豆精品 S� results were recently published in the journal .
UCF FSI Associate Scientist Noem铆 Pinilla-Alonso, who now works at the University of Oviedo in Spain, and Assistant Scientist Charles Schambeau led the research. The new findings build upon prior discoveries from Pinilla-Alonso and colleagues that detected carbon monoxide and carbon dioxide ice on trans-Neptunian objects (TNOs) for the first time earlier this year.
Those observations, paired with ones of Chiron, are creating foundational knowledge for understanding the creation of our Solar System, as these objects have largely remained unchanged since the Solar System was formed, Pinilla-Alonso says.
麻豆精品 S淎ll the small bodies in the Solar System talk to us about how it was back in time, which is a period of time we can 麻豆精品 S檛 really observe anymore, 麻豆精品 S� she says. 麻豆精品 S淏ut active centaurs tell us much more. They are undergoing transformation driven by solar heating and they provide a unique opportunity to learn about the surface and subsurface layers. 麻豆精品 S�
Since Chiron possesses characteristics of both an asteroid and a comet, it makes it rich for studying many processes that could assist in understanding them, she says.
麻豆精品 S淲hat is unique about Chiron is that we can observe both the surface, where most of the ices can be found, and the coma, where we see gases that are originating from the surface or just below it, 麻豆精品 S� Pinilla-Alonso says. 麻豆精品 S淭NOs don 麻豆精品 S檛 have this kind of activity because they 麻豆精品 S檙e too far and too cold. Asteroids don 麻豆精品 S檛 have this kind of activity because they don 麻豆精品 S檛 have ice on them. Comets, on the other hand, show activity like centaurs, but they are typically observed closer to the sun, and their comas are so thick that they complicate the interpretations of observations of the ices on the surface. Discovering which gases are part of the coma and their different relationships with the ices on the surface help us learn the physical and chemical properties, such as the thickness and the porosity of the ice layer, its composition, and how irradiation is affecting it. 麻豆精品 S�
The discovery of these ices and gases on an object as distant as Chiron 麻豆精品 S� observed near its farthest point from the sun 麻豆精品 S� is exciting because it could help contextualize other centaurs and provide insight into the earliest era of our Solar System, Schambeau says.
麻豆精品 S淭hese results are like nothing we 麻豆精品 S檝e seen before, 麻豆精品 S� he says. 麻豆精品 S淒etecting gas comae around objects as far away from the sun as Chiron is very challenging, but JWST has made it accessible. These detections enhance our understanding of Chiron 麻豆精品 S檚 interior composition and how that material produces the unique behaviors as we observe Chiron. 麻豆精品 S�
Schambeau specializes in studying centaurs, comets and other space objects. He analyzed the methane gas coma and determined that the outflowing gas detected was consistent with it being sourced from a surface area that was exposed to the most heating from the sun.
Chiron, first discovered in 1977, is characterized much better than most centaurs and comparatively is unique, Schambeau says. The newly analyzed information helps scientists better understand the thermophysical process going on in Chiron that produces methane gas, he says.
麻豆精品 S淚t 麻豆精品 S檚 an oddball when compared to the majority of other Centaurs, 麻豆精品 S� Schambeau says. 麻豆精品 S淚t has periods where it behaves like a comet, it has rings of material around it, and potentially a debris field of small dust or rocky material orbiting around it. So, many questions arise about Chiron 麻豆精品 S檚 properties that allow these unique behaviors. 麻豆精品 S�
The researchers concluded that the coexistence of the molecules in various states adds another layer of intrigue for studying comets and centaurs. The study also highlighted the presence of irradiated byproducts of methane, carbon monoxide and carbon dioxide that will require further research and could help scientists further reveal the unique processes producing Chiron 麻豆精品 S檚 surface composition.
Chiron originated from the TNO region and has traveled around our Solar System since its creation, says Pinilla-Alonso. The orbits of Chiron and many other large non-planetary objects occasionally experience close encounters with one of the giant planets where the gravitational pull from the planet changes the smaller object 麻豆精品 S檚 orbit, taking them all over our Solar System and exposing them to many different environments, she says.
麻豆精品 S淲e know it has been ejected from the TNO population and is only now transiting through the region of the giant planets, where it will not stay for too long, 麻豆精品 S� Pinilla-Alonso says. 麻豆精品 S淎fter about 1 million years, centaurs like Chiron typically are ejected from the giant planets region, where they may end their lives as Jupiter Family comets or they may return to the TNOs region. 麻豆精品 S�
Pinilla-Alonso notes that the JWST 麻豆精品 S檚 spectra showed for the first time Chiron 麻豆精品 S檚 plethora of ices with different volatilities and their formation processes, she says.
Some of these ices, such as methane, carbon dioxide, and water ice, may be primordial components of Chiron inherited from the pre-solar nebula. Others, such as acetylene, propane, ethane, and carbon oxide, could have formed on the surface because of reduction and oxidation processes, she says.
麻豆精品 S淏ased on our new JWST data, I 麻豆精品 S檓 not so sure we have a standard centaur, 麻豆精品 S� Pinilla-Alonso says. 麻豆精品 S淓very active centaur that we are observing with JWST shows some peculiarity. But they cannot be all outliers. There must be something that explains why they appear to all behave differently or something that is common between them all that we cannot yet see. 麻豆精品 S�
The analysis of Chiron 麻豆精品 S檚 gases and ices opens new frontiers and opportunities for exciting research, she says.
麻豆精品 S淲e 麻豆精品 S檙e going to follow up with Chiron, 麻豆精品 S� Pinilla-Alonso says. 麻豆精品 S淚t will come closer to us, and if we can study it at nearer distances and get better reads on the quantities and nature of the ices, silicates, and organics, we will be able to better understand how seasonal insolation variations and different illumination patterns can affect its behavior and its ice reservoir. 麻豆精品 S�
The JWST is the world 麻豆精品 S檚 premier space science observatory, and it is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe. The JWST is an international collaboration led by NASA with its partners the European Space Agency and the Canadian Space Agency.
Researchers 麻豆精品 S� Credentials
Pinilla-Alonso was a professor at FSI who joined UCF in 2015. Most of her work on this project was conducted while she was at UCF. Pinilla-Alonso also holds a joint appointment as a research professor in UCF 麻豆精品 S檚 and has led numerous international observational campaigns in support of NASA missions, such as New Horizons, OSIRIS-REx and Lucy. Pinilla-Alonso is a distinguished professor at the Institute for Space Sciences and Technologies in Asturias, within the Universidad de Oviedo. She received her doctoral degree in astrophysics and planetary sciences from the Universidad de La Laguna in Spain.
Schambeau is an assistant scientist who received his doctoral degree in physics with a concentration in planetary sciences in 2018 from UCF. He subsequently joined FSI where he expanded upon his work examining comets and centaurs as part of UCF 麻豆精品 S檚 .
