Posted on 06/05/2025 9:39:34 AM PDT by Red Badger
A groundbreaking discovery in the field of exoplanet research is forcing scientists to reconsider long-held theories about how planets form. An international team of astronomers, led by the University of Warwick, recently revealed the existence of TOI-6894b, a giant planet orbiting the ultra-low-mass star TOI-6894, in a study published in Nature Astronomy. This find has raised significant questions about the accuracy of the prevailing models of planet formation, which have long argued that gas giants like TOI-6894b cannot form around small stars.
Unlikely Host Star: The Tiny TOI-6894 At the heart of this discovery is TOI-6894, a red dwarf star with only 20% the mass of our Sun, making it significantly smaller and cooler than the stars typically known to host giant planets. These types of stars were previously thought incapable of hosting gas giants due to the limited amount of material in their protoplanetary disks. This makes the detection of TOI-6894b, a low-density gas giant orbiting such a star, all the more astonishing. The planet, which has a radius slightly larger than Saturn’s, is notable for its remarkably low mass, about 50% of Saturn’s. The star itself is now identified as the smallest mass star known to host a transiting giant planet, challenging previous assumptions about where such planets can form.
A Surprise Discovery Using TESS and ESO’s VLT The discovery of TOI-6894b is the result of an extensive search through data gathered by NASA’s TESS (Transiting Exoplanet Survey Satellite). Dr. Edward Bryant, Warwick Astrophysics Prize Fellow and the study’s first author, led the investigation, initially sifting through over 91,000 low-mass red-dwarf stars for potential giant planets. This enormous effort was followed up by observations made using one of the world’s largest telescopes, ESO’s Very Large Telescope (VLT), which ultimately confirmed the existence of TOI-6894b. Dr. Bryant expressed his excitement at the find, noting, “We did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation.”
New Planet Formation Theories The discovery has significant implications for how scientists think about planetary formation, especially the creation of gas giants. The most widely accepted model, core accretion theory, suggests that gas giants form when a planetary core grows large enough to attract surrounding gas, eventually leading to the rapid accretion of gas. However, this process has always been assumed to be unlikely around low-mass stars due to a lack of available material in the protoplanetary disk. The formation of TOI-6894b challenges this model. Dr. Bryant proposes that TOI-6894b could have formed through an intermediate core-accretion process, where the planet accreted gas steadily, without the core ever reaching a size large enough for a “runaway” gas accretion event. Alternatively, he suggests that a gravitationally unstable disk may have played a role. “In some cases, the disk surrounding the star will become unstable due to the gravitational force it exerts on itself. These disks can fragment, with the gas and dust collapsing to form a planet,” he explained.
Exploring the Atmosphere of TOI-6894b TOI-6894b also presents unique opportunities for scientists to study exoplanetary atmospheres. Unlike many known gas giants, such as the hot Jupiters, which are known for their scorching temperatures, TOI-6894b has a relatively cool surface temperature of only 420 Kelvin. This cooler temperature may offer a more favorable environment for studying atmospheric features. According to Professor Amaury Triaud from the University of Birmingham, one of the study’s co-authors, the planet’s atmosphere is likely dominated by methane chemistry, a rare trait among known exoplanets. “TOI-6894b likely presents a benchmark exoplanet for the study of methane-dominated atmospheres and the best ‘laboratory’ to study a planetary atmosphere containing carbon, nitrogen, and oxygen outside the solar system,” he said. Atmospheric observations of TOI-6894b are scheduled to take place with the James Webb Space Telescope (JWST) within the next year, which will allow astronomers to probe the planet’s atmosphere and perhaps discover ammonia for the first time in an exoplanet atmosphere.
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Webb Ping!....................
There’s always a non conformist in the group
New!
Its the mass that matters
TOI-6894. I like that name better than Uranus.
Or Ursphincter.
Or Urcolon.
Anti orbit type!
Thanks Red Badger.
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The more we find out the more we discover we don’t know...........
Funny how that works eh?
So at 50% of Saturn’s mass the planet is about 2.5 times Neptune which is 18% of Saturn’s mass. (Uranus comes in at about 15% of Saturn’s mass)
Between this story and the article about the planet which has two suns orbiting it’s orbit, I am thinking that God is trying to tell the astronomers something.
“planet formation theory” like God created the heavens and earth. There is a theory for ya.
He's telling them "I've got you covered! You never need to worry about being unemployed."
God loves astronomers.
I just ran the meatball program on the xplanets keyword. Big. Big Big. Real Big Big. Four minutes? Then the sort program said, "wth is this?" Anyway, I plan to look for more "origin" in the titles. Y'know, when I get done with this link you just sent me. :^)
X-Planets keyword, 2079 topics, including this one; selections:
Failed binary? Seems likely....
The science is settled. Until it’s not......and it never is.............
That’s what I was thinking.
Sounds like the Harry and MEghan saga.
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