James Webb Space Telescope discovers water in uncommon comet,unveiling a new mystery in the process. Water has been detected for the first time in a main belt comet, located in the asteroid belt between Mars and Jupiter.
After 15 years of efforts using various observation techniques, astronomers successfully detected water vapor around Comet Read using the space observatory. This discovery implies that water ice can be preserved in a relatively warmer region of our solar system. The findings were published in the journal Natureon Monday.
Comets are typically found in the Kuiper Belt and the Oort Cloud, icy regions located beyond Neptune's orbit. These regions serve as reservoirs for frozen materials left over from the early formation of our solar system.
Comets follow elongated orbits around the sun, spanning thousands of years, and develop streaming tails when they approach the sun. Their distinct fuzzy appearance and the presence of material tails distinguish them from asteroids.
Main belt comets are a unique subclass of comets found in the asteroid belt. Unlike typical comets, they have circular orbits around the sun within the asteroid belt. These comets display occasional comet-like characteristics, including the shedding of material that gives them a fuzzy appearance and a trailing tail.
Contrary to expectations, main-belt comets, located in the warmer region of the inner solar system, were thought to primarily eject dust rather than icy material through sublimation. However, a recent discovery challenges this notion by revealing that main-belt comets can indeed retain significant amounts of ice. This finding holds potential significance in understanding the abundance of water on Earth during its early history, supporting the theory that comets and water-rich asteroids may have collided with our planet, delivering water resources.
According to a statement made by study coauthor Stefanie Milam, Webb's deputy project scientist for planetary science at NASA’s Goddard Space Flight Center in Greenbelt, Maryland:
Our water-soaked world, teeming with life and unique in the universe as far as we know, is something of a mystery - we’re not sure how all this water got here. Understanding the history of water distribution in the solar system will help us to understand other planetary systems, and if they could be on their way to hosting an Earth-like planet.- Study coauthor Stefanie Milam, Webb deputy project scientist for planetary science at NASA’s Goddard Space Flight Center in Greenbelt, Maryland,
An image of a comet captured by the James Webb Space Telescope using its NIRCam instrument
In 2006, Henry Hsieh, a study co-author and senior scientist at the Planetary Science Institute in Tucson, Arizona, played a key role in the codiscovery of main belt comets, including Comet Read, which was among the comets initially identified to establish this subcategory.
By leveraging the precise data gathered by the Near-Infrared Spectrograph on the Webb Space Telescope, astronomers were able to detect the distinct signature of water vapor surrounding Comet Read shortly after its close encounter with the sun.
According to a statement made by lead study author Michael Kelley, astronomer and principal research scientist at the University of Maryland in College Park:
In the past, we’ve seen objects in the main belt with all the characteristics of comets, but only with this precise spectral data from Webb can we say yes, it’s definitely water ice that is creating that effect. With Webb’s observations of Comet Read, we can now demonstrate that water ice from the early solar system can be preserved in the asteroid belt.- Lead study author Michael Kelley, astronomer and principal research scientist at the University of Maryland in College Park
The discovery of Comet Read's lack of detectable carbon dioxide posed a new enigma. Unlike other comets, which typically consist of around 10% carbon dioxide in the material vaporized by the sun, Comet Read appears to be devoid of this ingredient.
Researchers suggest that the relatively warmer temperatures experienced in the main asteroid belt could potentially cause Comet Read to gradually lose its carbon dioxide over time, providing a possible explanation for this anomaly.
“Being in the asteroid belt for a long time could do it - carbon dioxide vaporizes more easily than water ice and could percolate out over billions of years,” Kelley said.
According to Kelley, another possibility is that Comet Read originated in a warmer region of the solar system where carbon dioxide was absent during its formation.
The team of observers is excited to examine additional main-belt comets and compare their characteristics with the data obtained from Comet Read using the James Webb Space Telescope. This comparative analysis will help determine if these celestial objects also lack carbon dioxide and pave the way for further investigations into the mysteries surrounding these rare comets.
“Now that Webb has confirmed there is water preserved as close as the asteroid belt, it would be fascinating to follow up on this discovery with a sample collection mission, and learn what else the main belt comets can tell us,” Milam said.