One might even be an interstellar visitor.
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Comet Hale-Bopp, as imaged from the Johannes-Kepler
Observatory in Linz, Austria, in April 1997. (Image credit: E. Kolmhofer, H.
Raab; Johannes-Kepler-Observatory, Linz, Austria under CC-BY-SA 3.0) |
Comets have mystified humanity for millennia, but with
the James Webb Space Telescope beginning science operations this month,
scientists hope to unravel secrets about these icy objects.
In a study led by Heidi Hammel, executive vice president
of the Association of Universities for Research in Astronomy and a Webb
interdisciplinary scientist, the James Webb Space Telescope's powerful infrared
instruments will be trained on three comets in the solar system. The goal will
be to analyze the comets' chemical compositions. Because comets are some of the
most primitive bodies in the solar system, this information could reveal clues
about the solar system's early life.
"We want to study comets with Webb because of the
telescope's very powerful capabilities in the near- and mid-infrared,"
Hammel said in a statement. "What makes those wavelengths of light
particularly powerful for cometary studies is that they allow us to study the
chemical makeup of this dust and gas that's come off of the comet's nucleus and
figure out what it is."
Hammel's team will observe three comets, each from a
different comet family. The first will be a Jupiter-family comet — potentially
Comet Borrelly, whose orbit is affected by the gas giant's gravity. The second
will be a main belt comet — likely Comet Read.
The third will be what's called a
"target-of-opportunity comet," meaning a comet that hasn't been
discovered yet. The researchers hope that this third comet will be spotted by Webb
before the beginning of this study and that it will belong to a different comet
family than the other two targets. In one possible scenario, the team would be
able to study an Oort Cloud comet that might have originated on the outskirts
of the solar system. Another possible "opportunity comet" might
originate from even farther afield, as did the interstellar objects 'Oumuamua
and C/2019 Q4 (Borisov).
"One of Webb's strengths is its ability to sense
faint objects, and that makes it a great tool to study these very rare and very
faint interstellar interlopers," Hammel said. "If we could glean
compositional information about its surface, that might open a whole new field
of study."
These three comets will be some of the first observed
by Webb, but they certainly won't be the last.
"Ultimately, these are just individual examples,
but over Webb's lifetime, we'll eventually observe many comets, and we'll have
lots of examples from these different classes, and we can compare them all to
each other," Michael Kelley, an associate research scientist at the
University of Maryland who is leading the observations of the Jupiter-family
and main belt comets, said in the statement. "With time — and in
conjunction with all the ground-based data that we've had and will continue to
obtain — we'll have a better understanding of where these comets come
from."
The study is part of Cycle 1 of the Guaranteed Time Observations program, which will occur during Webb's first year of operations.
Reference: Webb telescope
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