Unexpected New Quest for Astronomers After Webb’s Mysterious Find in Rare Main Belt Comet
This illustration of Comet 238P/Read exhibits the principle belt comet sublimating—its water ice vaporizing as its orbit approaches the Sun. This is important, because the sublimation is what distinguishes comets from asteroids, creating their distinctive tail and hazy halo, or coma. It is particularly vital for Comet Read, as it’s considered one of 16 recognized major belt comets discovered in the asteroid belt, versus the colder Kuiper Belt or Oort Cloud, extra distant from the Sun. Comet Read was considered one of three comets used to outline the category of major belt comets in 2006. Credit: NASA, ESA
The James Webb Space Telescope’s newest discovery is a story of two detections.
Solar system scientists took NASA’s James Webb Space Telescope on a treasure hunt in the asteroid belt, and what they didn’t discover turned out to be as vital as what they did. If a spectrum of doable chemical compounds serves as a map of what to look for, X marked the spot of water vapor on Comet Read – a long-sought clue in the bigger thriller of how Earth’s liquid water, and consequently life, first got here to be. However, carbon dioxide was lacking from the map, although it’s present in all different comets. So in addition to persevering with to pursue the historical past of historical water in the photo voltaic system, scientists have an surprising new quest on their arms, and will probably be searching for solutions in our cosmic yard.
This picture of Comet 238P/Read was captured by the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope on September 8, 2022. It shows the hazy halo, known as the coma, and tail which can be attribute of comets, versus asteroids. The dusty coma and tail outcome from the vaporization of ices because the Sun warms the principle body of the comet. Credit: NASA, ESA, CSA, Mike Kelley (UMD), Henry Hsieh (PSI), Alyssa Pagan (STScI)
NASA’s Webb Finds Water, and a New Mystery, in Rare Main Belt Comet
NASA’s James Webb Space Telescope has enabled one other long-sought scientific breakthrough, this time for photo voltaic system scientists finding out the origins of Earth’s abundant water. Using Webb’s NIRSpec (Near-Infrared Spectrograph) instrument, astronomers have confirmed fuel – particularly water vapor – round a comet in the principle asteroid belt for the primary time, indicating that water ice from the primordial photo voltaic system may be preserved in that area. However, the profitable detection of water comes with a brand new puzzle: in contrast to different comets, Comet 238P/Read had no detectable carbon dioxide.
“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,” stated Stefanie Milam, Webb deputy mission scientist for planetary science and a co-author on the research reporting the discovering. “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,” she added.
This graphic presentation of spectral information highlights a key similarity and distinction between observations of Comet 238P/Read by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope in 2022 and observations of Comet 103P/Hartley 2 by NASA’s Deep Impact mission in 2010. Both present a definite peak in the area of the spectrum related to water. Finding this in Comet Read was a major accomplishment for Webb, as it’s in a distinct class of comets than Jupiter-family comets like Hartley 2, and this marks the primary time {that a} fuel has been confirmed in such a major belt comet. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)
Comet Read is a major belt comet – an object that resides in the principle asteroid belt however which periodically shows a halo, or coma, and tail like a comet. Main belt comets themselves are a reasonably new classification, and Comet Read was one of many authentic three comets used to establish the category. Before that, comets had been understood to reside in the Kuiper Belt and Oort Cloud, past the orbit of Neptune, the place their ices may very well be preserved farther from the Sun. Frozen materials that vaporizes as they method the Sun is what offers comets their distinctive coma and streaming tail, differentiating them from asteroids. Scientists have lengthy speculated that water ice may very well be preserved in the hotter asteroid belt, contained in the orbit of Jupiter, however definitive proof was elusive – till Webb.
“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,” defined astronomer Michael Kelley of the University of Maryland, lead creator of the research.
“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,” Kelley stated.
Image of Comet 238P/Read captured by the Webb Telescope’s NIRCam (Near-Infrared Camera), with compass arrows, scale bar, and colour key for reference.
The north and east compass arrows present the orientation of the picture on the sky. Note that the connection between north and east on the sky (as seen from under) is flipped relative to path arrows on a map of the bottom (as seen from above). A scale bar is labeled 3,000 kilometers and 2,000 miles.
This picture exhibits near-infrared wavelengths of sunshine which have been translated into visible-light colours. The colour key exhibits the filter used when accumulating the sunshine.
Credit: NASA, ESA, CSA, Mike Kelley, Henry Hsieh (PSI), Alyssa Pagan (STScI)
The lacking carbon dioxide was a much bigger shock. Typically, carbon dioxide makes up about 10 % of the risky materials in a comet that may be simply vaporized by the Sun’s warmth. The science staff presents two doable explanations for the dearth of carbon dioxide. One risk is that Comet Read had carbon dioxide when it fashioned however has misplaced that due to heat temperatures.
“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 stated. Alternatively, he stated, Comet Read could have fashioned in a very warm pocket of the photo voltaic system, the place no carbon dioxide was obtainable.
The subsequent step is taking the analysis past Comet Read to see how different major belt comets evaluate, says astronomer Heidi Hammel of the Association of Universities for Research in Astronomy (AURA), lead for Webb’s Guaranteed Time Observations for photo voltaic system objects and co-author of the research. “These objects in the asteroid belt are small and faint, and with Webb we can finally see what is going on with them and draw some conclusions. Do other main belt comets also lack carbon dioxide? Either way, it will be exciting to find out,” Hammel stated.
Co-author Milam imagines the chances of bringing the analysis even nearer to house. “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.”
The research is revealed in the journal Nature.
Reference: “Spectroscopic identification of water emission from a main-belt comet” by Michael S. P. Kelley, Henry H. Hsieh, Dennis Bodewits, Mohammad Saki, Geronimo L. Villanueva, Stefanie N. Milam and Heidi B. Hammel, 15 May 2023, Nature.
DOI: 10.1038/s41586-023-06152-y
