James Webb Space Telescope unveils fiery origins of a distant, hellish exoplanet

[Admin]

Astronomers using the James Webb Space Telescope have uncovered the fiery origin of WASP-121b, a distant exoplanet stretched by tidal forces and rich in chemical clues that reveal its dramatic journey.

James Webb Space Telescope unveils fiery origins of a distant, hellish exoplanet : Read more

 

[rod]

Interesting, WASP-121 b must migrate inwards and then stop leaving it where we see it today according to the report ( no in-situ formation). Exactly where it started at relative to host star in AU, how long it took to migrate inwards, and then stop where it is at today, I did not read. We have properties and details here, https://exoplanet.eu/catalog/wasp_121_b--2410/, "Semi-Major Axis 0.02544 AU" My observation. The age of WASP-121 b system not shown too.

My observation. Exoplanets continue to offer up challenges for accretion disc models used to explain their origins.

Discovery of giant planet orbiting tiny star challenges theories on planet formation, https://phys.org/news/2025-06-discovery-giant-planet-orbiting-tiny.html

 

[billslugg]

Iron rain falls not only on Wasp-121b-2410, but on this planet too. I have found frozen iron raindrops in Georgia, USA.
Since I retired from industry in 1998 I have walked the highways, getting my exercise, picking nails, helping to reduce flat tires. On three occasions I have found where tractor trailers have lost wheel bearings due to overheating. The early stage of the process involves the rollers heating up and softening. The gap at top opens up and they fly out onto the road, badly deformed. They might be found over a mile long stretch of highway. Once the bearing inner and outer races are rubbing, molten steel begins forming and rimming the cavity. When the vehicle comes to a stop, the molten iron runs out. The early blobs are elongated with tails since the truck was still moving . It all comes out over 100 meters or so. When stopped and the last few drops fall out, they will squish slightly as they hit the ground, then solidify quickly. I have found dozens, some as small as 8 mm in diameter, 5 mm tall, 1.8 grams.

 

[Helio]

This baby is not too far beyond the Roche limit, with the limit at 1/4 its current orbit.

Interesting, WASP-121 b must migrate inwards and then stop leaving it where we see it today according to the report ( no in-situ formation). Exactly where it started at relative to host star in AU, how long it took to migrate inwards, and then stop where it is at today, I did not read.

You're likely right about the migration. Wiki shows the star with a rotation velocity of 11.9 kps, which, I think, works out be a rotation period of about 150 hours, which is 5x slower than the exo.

Thus, the tidal stress should reel it in in a relatively short time.

 

[Helio]

Iron rain falls not only on Wasp-121b-2410, but on this planet too. I have found frozen iron raindrops in Georgia, USA.
Since I retired from industry in 1998 I have walked the highways, getting my exercise, picking nails, helping to reduce flat tires.

I seem to always reduce my flat tires on one side.

 

[billslugg]

On heavily traveled, 4 lane highways, little pedestrian traffic, there are about 500 tire hazards per mile, each way. One every ten feet. I count nails at least an inch long, glass shards, skinny bolts. Almost all of them are outside the travel lane, in the emergency lane. One percent of them are inside a travel lane. Nails are safely run over by a non-powered tire. No rubber flexure in the outgoing release. A powered tire compresses the rubber in front, on release it tosses the nail about 6" backwards. If it flips upright it can be in position for the rear tire to be damaged. If the rear tire hits the head then it only bends the nail. I have replicated this in my driveway. Coins also fold. I have collections. The moral of the story is to slow WAY down before you drive into the emergency lane. This has been a public service message.

 

[Helio]

Bill, have you passed this issue to your DOT and political officials? I complained to my county comm. about major road cracks that needed crack sealing else the road structure (base) would soon deteriorate. A week later the PWD spent 3 days crack sealing.

 

[Unclear Engineer]

How do we know that WASP-121 b has stopped migrating inward? Maybe it is still migrating now, and will end up getting inside the Roche limit in the future, Since we know the rotation rate of the star and the orbital period of the planet, shouldn't we already have prediction about the time for the demise of the planet into its star?

Of course, none of that provides any answer to how such a large planet formed around such a small star. On the other hand, with most stars forming in binary pairs, why is it a surprise that some pairs might be a small star and a large planet, instead of 2 small stars?

 

[rod]

Properties for WASP-121 b and host star are found here, https://exoplanet.eu/catalog/wasp_121_b--2410/

The exoplanet is some 1.184 Mjup and star is 1.353 solar mass. 0.02544 AU is where the semi-major axis is seen. That is very close to the host star, nothing like our solar system configuration.

 

[Helio]

How do we know that WASP-121 b has stopped migrating inward? Maybe it is still migrating now, and will end up getting inside the Roche limit in the future,

Exactly where I was heading. The tidal loading will continue to draw it in. So will it be within the Roche limit when its orbital speed matches the star? Of course, as it migrates it only gets worse.

Of course, none of that provides any answer to how such a large planet formed around such a small star. On the other hand, with most stars forming in binary pairs, why is it a surprise that some pairs might be a small star and a large planet, instead of 2 small stars?

Early migration seems to be the mainstream view for the majority of stellar systems. Accretion disks rotate slower than Keplerian motions, thus as a body forms it will fall inward to Keplerian rates. But it will also continue to plow through the slower disk as it continues to accrete, causing more inward migration.

There were likely sister solar planets that “saw the light of day, but all too close!”

Thus is true for planetary formations. Jupiter likely saw its inner moons auger in. Io, Europa and Ganymede are in resonance, which keep them from their demise.

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