Comets are uncommon within the asteroid belt between the planets Mars and Jupiter. However some comets do reside there, together with Comet Learn (238P/Read). Asteroids are usually rocky or metallic. Not like them, Comet Learn – an icy physique – generally seems fuzzy, displaying, like different comets, a coma and a tail. On Could 15, 2023, NASA said the Webb space telescope has taken a detailed have a look at Comet Learn. Webb confirmed water vapor, a primary for a comet within the asteroid belt. Extra sudden was what Webb didn’t discover. It discovered no signal of carbon dioxide, a fuel anticipated and noticed in most comets.
A staff of scientists within the U.S. published the peer-reviewed outcomes on Could 15, 2023, in Nature.
Bizarre comet 238P/Learn
Comets are usually wealthy in water vapor and water ice, in addition to fuel and dust. Scientists assume they could even have brought much of Earth’s original water to our planet billions of years in the past. However on the subject of the rarer comets in the principle asteroid belt, proof of water vapor or ice has been onerous to come back by … till now.
For the primary time, water vapor has been definitively detected on a comet – Comet Learn – in the principle asteroid belt. Lead creator Michael Kelley of the College of Maryland said:
Up to now, we’ve seen objects in the principle belt with all of the traits of comets, however solely with this exact spectral information from Webb can we are saying sure, it’s undoubtedly water ice that’s creating that impact. With Webb’s observations of Comet Learn, we will now exhibit that water ice from the early solar system will be preserved within the asteroid belt.
Lacking carbon dioxide
There was, nonetheless, one other consequence that shocked scientists. Webb discovered no carbon dioxide (CO2) on the comet. The paper stated:
Right here, we current JWST [James Webb Space Telescope] observations which clearly present that main-belt comet 238P/Learn has a coma of water vapor, however lacks a major CO2 fuel coma.
Carbon dioxide tends to compose about 10% of the risky materials in comets. So why is it lacking in Comet Learn?
The researchers pose two potential eventualities to elucidate the lacking carbon dioxide. The primary chance is that the comet did have it a very long time in the past however ended up shedding it due to the hotter temperatures within the asteroid belt. (Comets typically reside and originate within the Kuiper Belt and Oort Cloud, out previous Neptune). As Kelley defined:
Being within the asteroid belt for a very long time may do it; carbon dioxide vaporizes extra simply than water ice, and will percolate out over billions of years.
The opposite concept is that Comet Learn originated in a hotter area of the solar system the place there was no carbon dioxide to start with.
Extra observations and perhaps even a mission?
The outcomes are fascinating, however do they characterize asteroid-belt comets basically, or is Comet Learn merely uncommon? To seek out out, astronomers will now use Webb to have a look at different comets in that a part of the solar system as nicely. This can be a part of Webb’s Guaranteed Time Observations. Co-author Heidi Hammel is with the Affiliation of Universities for Analysis in Astronomy (AURA). She said:
These objects within the asteroid belt are small and faint, and with Webb we will lastly see what’s going on with them and draw some conclusions. Do different main-belt comets additionally lack carbon dioxide? Both manner it is going to be thrilling to search out out.
There’s even the opportunity of sending a robotic spacecraft mission out to considered one of these comets. Co-author Stefanie Milam, Webb deputy challenge scientist for planetary science, surmised:
Now that Webb has confirmed there’s water preserved as shut because the asteroid belt, it might be fascinating to observe up on this discovery with a sample-collection mission and be taught what else the principle belt comets can inform us.
The findings present how comets aren’t all alike as a lot as we’d are inclined to assume. The variations, and similarities, between comets in varied components of the solar system can present invaluable clues as to how they – and the solar system general – first shaped. And perhaps even how life first originated on Earth, and maybe elsewhere in our sun’s household of worlds.
Backside line: The Webb telescope has noticed Comet Learn, a bizarre comet in the principle asteroid belt. Among the many findings … water vapor, sure. However carbon dioxide, no.
Source: Spectroscopic identification of water emission from a main-belt comet
