The James Webb Space Telescope detects outgassing from the main belt comet

After 15 years of attempts, researchers using the James Webb Space Telescope (JWST) have succeeded for the first time in detecting the release of water gases from a main belt comet.

It was posted recently nature Paper” direct detection of water from a main belt comet with JWST” led by Michael Kelly of the University of Maryland reported the first direct spectroscopic detection of water emissions from a main belt comet called Comet Read. Planetary Science Institute Senior Scientist Henry Hsieh is a co-author on the paper.

Main belt comets are a rare subclass of comets that mostly possess circular orbits is entirely limited to main asteroid belt between the orbits of Mars and Jupiter, but they exhibit comet-like behavior — ejections of material that create fuzzy appearances and often tails — that astronomers believe result from sublimation — or ice going directly into gas — of icy material.

Only dust has been detected by main-belt comets, despite numerous attempts to detect escaping gases that must also accompany sublimation-powered comet activity. Most main belt asteroids are not expected to contain much ice, given their location in the warm inner solar system where they are thought to have resided for billions of years.

For comparison, most other comets that display sublimation-induced activity spend large portions of their time in the cold outer solar system on extremely long orbits that only occasionally pass through the inner solar system. Given these considerations, doubts persisted as to whether main belt comets could really be icy. So far.

“Since the discovery of main-belt comets, we have gathered a large body of evidence that their activity results from sublimation, but until now, it has all been indirect. This new result from JWST represents the first direct evidence of sublimation in the form of outgassing from water – Or outgassing of any kind — from a main belt comet, after studies dating back to 2008 detected outgassing in main belt comets using some of the world’s largest ground-based telescopes, explained Hsieh, who led the discovery of main belt comets as a new type of comet in 2006. .

In the paper, Hsieh and his colleagues also found that Comet Read, and thus likely other main belt comets as well, have a fundamentally different chemical composition than other comets, showing almost none. Carbon Dioxide, a common component of cometary outgassing, relative to the amount of water present. Whether it experienced different formation conditions or evolutionary history,

Comet Read is unlikely to be a recent interloper in the asteroid belt of the outer solar system. Based on these findings, main-belt comets appear to represent a sample of volatiles currently not represented in observations of classical comets and the meteorite record, making them important for understanding the volatile stock of the early solar system and its subsequent evolution.

“Since significant water ice—a major constituent of the volatile matter that produces activity in ‘classical’ comets from the outer solar system—is not expected in main-belt asteroids due to how close they are to the Sun, there has always been some skepticism about whether belt comet activity The main result is the sublimation of water ice rather than some other process that does not involve ice, such as impacts or material being hurled into space by rapidly spinning asteroids.”

“Water in main belt comets is important because bodies from the main belt asteroids have been suggested as a possible source of Earth’s water in the early solar system, as modern-day main belt comets seem to provide an opportunity to test this hypothesis. This only works if they actually contain ice.” Watery Confirmation of outgassing in at least one main-belt comet suggests that identifying the origin of Earth’s water from main-belt comets is a viable possibility,” Hsieh said.

The team used JWST to monitor the reading soon after close approach to the Sun, when outgassing was expected to be at its strongest, taking both photographic and spectral observations in the near-infrared wavelengths in order to look for spectral hallmarks of water vapor and other common gases produced by the sublimation of comets.