Arthur T Knackerbracket has processed the following story:
In a study recently published in Nature Astronomy, the researchers detail how they tested the unparalleled capabilities of Webb’s Mid-Infrared Instrument (MIRI) and observed the entire orbit of WASP-43b, a giant, gas-filled exoplanet. These “phase curve” observations, conducted during Webb’s inaugural year, revealed the temperature distribution across the entire planet and shed light on the planetary climate. The researchers found thick clouds and a surprising lack of methane on the planet’s nightside, and ubiquitous water presence throughout its atmosphere. This is the first time clouds have been inferred on the nightside of the planet; they were found at much higher altitudes in the planetary atmosphere compared to typical clouds observed on Earth.
WASP-43b shares a comparable size and mass with Jupiter, yet it diverges significantly in its planetary characteristics. Its host star, WASP-43A, is much cooler and redder than our sun and is around 86 lightyears away from the Earth. WASP-43b orbits very closely to its star, resulting in a year that lasts only 19.5 hours. This close proximity causes the planet’s rotation to synchronize with its orbit, with one side always facing the star, similar to the tidal locking observed with our moon. As a result, one-half of the planet (dayside) is permanently illuminated and very hot, while the other half (nightside) is permanently shadowed and much colder.
[...] The team found that WASP-43b’s permanently illuminated dayside is as hot as 2285°F (1250°C), while the planet’s nightside, although permanently shadowed, was still very hot 1115°F (600°C).
“The absence of direct sunlight on the planet’s nightside causes significant temperature differences between the day and night sides, which prompts the formation of exceptionally strong winds,” said Dobbs-Dixon, an expert in 3-dimensional atmospheric models and heat redistribution of exoplanetary atmospheres. “While winds on Earth form in a similar manner due to variations in temperature, the close proximity of WASP-43b to its host star results in much more extreme temperature differences. This produced winds of thousands of kilometers per hour, far surpassing those on Earth, crucial for the distribution of heat and shaping the overall planetary climate.”
In addition, comparisons of the planet’s temperature map with complex 3D atmospheric models demonstrated that this temperature contrast is stronger than expected for a cloud-free atmosphere. This suggests that the planet’s nightside is shrouded in a thick layer of clouds that blocks much of the infrared radiation that would otherwise be observed. Unlike Earth’s water clouds, the clouds on this extremely hot planet resemble dust and are composed of rocks and minerals.
Surprisingly, despite this thick layer of clouds, the JTEC-ERS team also detected clear signals of water on the planet’s nightside. This allowed them to determine, for the first time, the cloud height and thickness, unveiling their unusual altitude and density compared to Earth’s clouds. The researchers also detected wind-driven mixing, called “chemical disequilibrium,” that swiftly transports gas throughout the planet’s atmosphere and results in uniform atmospheric chemistry.
Reference: Bell, T.J., Crouzet, N., Cubillos, P.E. et al. Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b. Nat Astron 8, 879–898 (2024). https://doi.org/10.1038/s41550-024-02230-x
(Score: 1, Interesting) by Anonymous Coward on Sunday July 28 2024, @10:16AM (5 children)
> WASP-43b’s permanently illuminated dayside is as hot as 2285°F (1250°C), while the planet’s nightside, although permanently shadowed, was still very hot 1115°F (600°C).
From http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/meltrock.html [gsu.edu] Typical melting points of rock:
Sorry for poorly formatted table (looks better at the source). Molten rock is called magma on Earth, but perhaps the combination of pressure and higher gravity keeps the rock solid on WASP-43b? Or it's made of something other than the sorts of rock we've found here (and around our Sol system.
(Score: 1, Informative) by Anonymous Coward on Sunday July 28 2024, @12:07PM (4 children)
I think the molten rock vaporize and make it into the atmosphere because they have rock clouds! (from TFA)
(Score: 3, Insightful) by Unixnut on Sunday July 28 2024, @03:48PM (3 children)
but only on the (relatively) hot side. The "cold" side is at 600°C, where 3/4 of the GP's list would condense/solidify. So the planet may have some king of rock convection, where rock is vaporised, is carried to the cold side by the winds and condenses again, making its way across the liquid surface rock.
Interesting, but a lot of this is still inferred speculation.
(Score: 1, Insightful) by Anonymous Coward on Sunday July 28 2024, @05:31PM
> Interesting, but a lot of this is still inferred speculation.
Did you mean--
Interesting, but a lot of this is still infrared speculation.(grin)
I like the idea that the hot side vaporizes and condenses on the cold side. Next question is how long it takes for a rock in the middle of the cold side to be buried in more condensate and eventually migrate all the way through the planet and be vaporized on the hot side...to repeat the cycle...?
What shape would such a planet take? The liquid hot side seems like it would be near spherical due to gravity, but the cold side could be odd, depending on how far the vaporized rock travels past the day/night line before it condenses. If it condenses quickly, the back side could be a giant crater, perhaps with planet-scale avalanches from the rim into the deep center.
Too bad Hal Clement (https://en.wikipedia.org/wiki/Mission_of_Gravity) isn't around, I bet he could work this planet into a good yarn.
(Score: 1) by Opyros on Sunday July 28 2024, @06:38PM (1 child)
I know that was a typo, but now I want to be crowned King of Rock Convection.
(Score: 0) by Anonymous Coward on Sunday July 28 2024, @09:48PM
OP here.
Actually, it was meant as a slightly lame pun:
inferred: deduce from evidence rather than explicit statements.
infrared: from tfs, "Webb’s Mid-Infrared Instrument (MIRI)"