2023-05-23 11:29:00
He james space telescope Webb (JWST, for its acronym in English) is a space observatory that has been developed mainly by NASA, considered the successor to the Hubble Space Telescope, with far superior technological capabilities.
Now, thanks to the telescope’s Near Infrared Spectrograph (NIRSpec) instrument, it has been possible to verify a milestone in the history of astronomy: the presence of water vapor around a comet in the main asteroid belt (a vast region of our Solar System located between the orbits of Jupiter and Mars).
The analyzed comet in question is 238P/Read.
The tail of comets is water
He 238P/Read it is particularly notable because it is one of the few comets known to reside in the main asteroid belt, representing an exception to the general rule that comets come from the outer solar system.
Until now, the composition of the iconic tail that a comet leaves behind as it streaks through space was unknown. Now we know that it is water vapor. But there is more: the telescope’s instruments showed that 238P/Read does not have carbon dioxidea component that normally makes up 10% of the matter that evaporates as it approaches the Sun.
A peculiarity of asteroids is that they release water and carbon dioxide as they heat up (evaporation process). There are two possible assumptions. One is that the comet may have lost all its carbon dioxide before being detected by the instruments on James Webb. The other is that it could have originated in an “exceptionally warm” region of the solar system where no carbon dioxide was present.
In any case, thanks to James Webb’s observations of Comet Read, we can now confirm that water ice from the early Solar System can be preserved in the asteroid belt. However, the investigation continues, and the questions seem to multiply.
New Horizons
With James Webb in orbit, it is now feasible to examine other main belt comets that are so tiny and faint that they were previously unattainable for study in order to answer these new questions.
So the next step is to take the investigation beyond Comet Read to see how it compares to other comets in the main belt, according to astronomer Heidi Hammelof the Association of Universities for Research in Astronomy (AURA), head of Webb’s Guaranteed Time Observations program for solar system objects and co-author of the study:
“Now that Webb has confirmed that there is preserved water as close as the asteroid belt, it would be exciting to follow up on this discovery with a sample-collection mission and learn what else main-belt comets can tell us.”
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