2023-05-16 13:06:28
We no longer really count the discoveries already made thanks to the James-Webb space telescope. But the precision of the data it returns sometimes also reveals some unsuspected mysteries. Like the one hidden by the amazing comet Read.
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[EN VIDÉO] What is a comet? Where do they come from? How many are they? Their name comes from the Greek komêtês meaning “hairy…
Comet Read — or more officially 238P/Read — is the name of an asteroid in the main belt, the one that lies between the orbits of Mars and Jupiter. An asteroid that periodically appears with a tail. Like a comet. And it is one of three objects to have defined a new category of comets. The comets of the main belt, precisely. Because before their discovery, astronomers believed that comets necessarily came from beyond Neptune’s orbit. From a region where ice can hold. This ice which forms their tail, when they approach the Sun.
The discovery in 2005 of comet Read and its companions led to the idea that water ice could also be preserved in the main asteroid belt. Data collected by the James-Webb Space Telescope (JWST) and its Near-Infrared Spectrograph (NIRSpec) finally confirm it. “In the past, we have seen objects with all the characteristics of comets. Today we can say yes, it is definitely the water ice that creates this effect”explains Michael Kelley, an astronomer at the University of Maryland (United States), in a communiqué. What a better way to understand the distribution of water in our solar system. But also potentially in other planetary systems. And have more clues that could tell us that some are home to planets similar to ours.
Water, but no CO2
What surprised the researchers the most was that they did not detect carbon dioxide around comet Read. Even as the CO2 constitutes 10% of the volatile matter of classical comets. There are two possible explanations for this. The comet may have lost its CO2 under the effect of the relatively warm temperatures prevailing in the main asteroid belt. Because carbon dioxide vaporizes more easily than water ice. The comet could also have formed in a particularly hot pocket of the Solar System in which there was no CO2.
To unravel the threads of this new mystery, the researchers now intend to exploit the capabilities of the James-Webb space telescope to explore the other comets in the main belt. And why not design a sample recovery mission on comet Read…
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