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The ‘forbidden’ planet challenges current understanding of planetary formation

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from: Tanya Banner

A research team discovers a planetary system that turns previous research on its head: a very large gas giant orbiting a red dwarf.

Washington, DC – Researchers know of more than 5,000 planets outside our solar system, or so-called exoplanets. Among them there are many celestial bodies that look very strange – for example, A Planet Hell, whose surface consists of liquid lava. last An exoplanet is considered a “home planet” for research. Now, a research group from the Carnegie Institution for Science in Washington, D.C., has discovered an exoplanet that baffles researchers and challenges long-held notions of how planets form.

It used a team of astronomers led by Shubham Kanodia NASAThe Tess space telescope has detected a very unusual planetary system: a small red dwarf star TOI-5205 orbiting a large gas planet. Was sich erst einmal nicht ungewöhnlich anhort, ist für die Forschenden spektakular: Zwar haben rote Zwergsterne im Durchschnitt mehr Planeten als größere Sternentypen – doch bisher ging die Forschung davon aus, dass es unwahrscheinlich ist, dass im Orbit um einen roten Zwergstern Gasplan ein großer enthen großer Could you.

An exoplanet too large for the star it orbits

But that’s exactly what Kanodia and his team discovered: the exoplanet TOI-5205b orbits the tiny red dwarf star TOI-5205. “According to our current understanding of planetary formation, TOI-5205b should not exist; it is a ‘forbidden’ planet,” the researcher explains in one. communication. Research work was on the topic in the specialized magazine The Astronomical Journal published.

Red dwarf stars are smaller than our sun, half as hot and red. They have very low brightness but extremely long lifetimes and are among the most common stars in the Milky Way. So far, few gas planets have been discovered around old dwarf stars – but no gas giant has been found around a young dwarf star like TOI-5205. “TOI-5205’s host star is four times the size of Jupiter, yet it somehow managed to create a planet the size of Jupiter, which is surprising,” notes Kanodia.

family name: TOI-5205
He writes: red dwarf star
Size / Mass: 40% from the sun
Temperature: 3100°C (Sun: 5500°C)
Planets: One known number so far

The research team is amazed to search in space

To illustrate the proportions, the research team compares it to fruit: in this case, Jupiter orbiting the sun would be a pea orbiting a grapefruit. The researchers compared the newly discovered planetary system to that of a pea orbiting a lemon. According to the research team, the gas planet TOI-5205b blocks about seven percent of the light from its star when it passes in front of it.

Artist’s impression of the massive gas planet TOI-5205b orbiting the small red dwarf star TOI-5205. © Catherine Cain/Carnegie Endowment for Science

Planets form in a rotating disk of gas and dust that surrounds young stars. According to current theory, a gaseous planet would need about ten Earth masses of material to form the massive rocky core in its interior. Then it collects large amounts of gas in its surroundings and grows larger and larger.

TOI-5205b exoplanet should not actually exist

“The existence of TOI-5205b expands what we know about the disks in which these planets were born,” Kanodia explains. If there is not enough rocky material to begin with to form the core, the gas giant cannot form. According to the expert, even if the disk evaporates before the massive core is formed, no gaseous planet will form. “However, TOI-5205b was formed despite these guardrails,” Kanodia Miracle said. The research team hypothesizes that in the protoplanetary disk around the star TOI-5205, due to its size, there should only be four to five clumps of dust and rock.

In the future, the research group wants to further investigate the newly discovered exoplanet using the James Webb Space Telescope. Among other things, the new telescope can detect whether the planet has an atmosphere and what it looks like. (unpaid bill)