- 4410 - CENTAURS - are small planetary bodies ? - These planetary bodies orbit between Jupiter and Neptune and have baffled astronomers for sharing characteristics with both asteroids and comets. Centaurs got their name after the mythical half-horse, half-human creatures called centaurs due to their dual characteristics.
------------------------- 4410
- CENTAURS - are
small planetary bodies ?
-
- The NASA’s James Webb Space Telescope
(JWST) has conducted a first-time detection of carbon dioxide in a Centaur,
this one designated “39P/Oterma”. A Centaur is a small planetary body that
orbits between Jupiter and Neptune and frequently crosses the orbits of one or
more of the gas giant planets within our solar system.
-
- While no Centaur has been imaged up-close,
they typically exhibit a combination of attributes between comets and
asteroids. While carbon monoxide has been detected in two known centaurs, this
recent discovery could mark a turning point in how scientists understand the
formation, evolution, and composition of not only Centaurs, but of the early
solar system.
-
- Centaurs are important to study since they
are fairly well-preserved objects in space that can provide insight on the
chemical composition and physical processes of the early solar system.
-
- Centaur 39P/Oterma was discovered on April
8, 1943, by Finnish astronomer, Dr. Liisi Oterma, who was the first woman to
earn PhD in astronomy in Finland, along with being the first woman PhD of the
faculty of sciences at Turku University. While 39P/Oterma has long been
classified as an inactive comet, it currently exhibits a Centaur-like orbit
between Jupiter and Saturn, meaning it doesn’t approach the Sun, and has a
radius of approximately 1.37 to 1.55 miles.
-
- 39P/Oterma is what we call an active
centaur, a centaur that develops a coma and a tail like a normal comet. Since they are active, we can use
spectroscopy to observe molecules in their coma to gain insights into their
composition. 39P was chosen as one of our targets because it would be active
during the time of the proposed observations.
-
- JWST used Near-Infrared Spectrograph
(NIRSpec) instrument and was supported by ground-based observations from the
Gemini North Observatory and Lowell Discovery Telescope to investigate the
characteristics of 39P/Oterma while it was orbiting close to its perihelion
(closest distance to the Sun) at 5.82 astronomical units (AU) from the Sun in
July 2022.
-
- For context, the perihelion of 39P/Oterma
has gradually increased since its discovery: 3.39 AU (1958), 5.47 AU (1983),
and 5.71 AU (2023), and is projected to reach 5.91 AU and 6.15 AU in 2042 and
2246, respectively.
-
- After analyzing the JWST NIRSpec data, the
researchers confirmed the first detection of carbon dioxide in any Centaur, and
the lowest amount of carbon dioxide ever detected in any Centaur or comet. They
also did not detect traces of water or carbon monoxide, which are traditionally
detected in Centaurs.
-
- These results are important because they
show that thanks to the impressive capabilities of JWST, we are able to see low
production rates of a relatively small object that is very far away. And, though the production rates are low, it
shows a different chemical behavior from another Centaur, 29P/SW1, seen at a
similar distance (~6 AU). This difference in chemical behavior could be from
the very different sizes of Centaurs 29P and 39P, or from having different
orbital histories, or starting out with different compositions, or possibly a
combination of all of these.
-
- The finding of carbon dioxide in a Centaur
could be a game changer in terms of understanding the compositions and
characteristics of Centaurs, asteroids, and comets throughout the solar system,
along with potentially gaining better insight into the formation and evolution
of the solar system.
-
-
March 28, 2023 CENTAURS
- are small planetary bodies
? 4410
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--------------------- --- Thursday, March 28,
2024
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