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Discovery could significantly narrow the search for space creatures

Discovery could significantly narrow the search for space creatures

Illustration of a red dwarf star orbiting a hypothetical exoplanet. Red dwarfs explode with intense flares that over time can strip the atmosphere of a nearby planet or render the surface unsuitable for life as we know it. Credits: NASA/ESA/STScI/G. Bacon

An Earth-like planet orbiting the M dwarf, the most common type of star in the universe, appears to have no atmosphere at all. This discovery could cause a major shift in the search for life on other planets.

Because m-dwarfs are so common, this discovery means that many planets orbiting these stars may also lack atmospheres and therefore are unlikely to harbor life.

The work that led to the revelations about the non-atmospheric planet GJ 1252b is detailed here: Astrophysical Journal Letters.

This planet orbits its star twice during a single day on Earth. It is slightly larger than Earth and much closer to its star than Earth is to the sun, making GJ 1252b both very hot and uninhabitable.

“The pressure from the stellar radiation is so great, enough to blow up a planet’s atmosphere,” said Michelle Hill, UC Riverside astrophysicist and co-author of the study.

Earth also loses some of its atmosphere over time because of the sun, but volcanic emissions and other carbon cycle processes help to replenish what has been lost, making the loss barely noticeable. However, a planet closer to a star cannot continue to replenish the lost amount.

That’s the fate of Mercury in our solar system. It has an atmosphere, but an extremely thin atmosphere of atoms ejected from its surface by the sun. The extreme heat of the planet causes these atoms to escape into space.






Illustration of the atmosphere being removed from a planet by a nearby star. Credit: NASA

To determine that GJ 1252b lacks an atmosphere, astronomers measured infrared radiation from the planet as its light was obscured during a secondary eclipse. This type of eclipse occurs when a planet passes behind a star and the light of the planet, as well as reflected from its star, is blocked.

The radiation revealed the planet’s scorching daytime temperatures, which were estimated to reach 2,242 degrees Fahrenheit—so hot that gold, silver, and copper would all melt on the planet. The heat, combined with the low surface pressure, convinced the researchers that there was no atmosphere.

The researchers concluded that even with an enormous amount of carbon dioxide trapping heat, the GJ 1252b would still not be able to hold onto an atmosphere. “The planet could have 700 times more carbon than Earth has and still wouldn’t have an atmosphere. It will build up initially, but then thin and erode,” said Stephen Kane, UCR astrophysicist and co-author of the study.

M dwarf stars tend to have more glare and activity from the sun, making them less likely to cling to the atmospheres of closely surrounding planets.

“The condition of this planet could be a bad sign for planets even further away from such stars,” Hill said. “This is something we will learn from the James Webb Space Telescope, which will look at planets like this one.”

Hill’s work on this project was supported by a grant from Future Researchers in the NASA Earth and Space Science and Technology program.

Earth has 5,000 stars around the sun, most of which are M dwarfs. Even if the planets orbiting them can be completely ignored, there are about 1,000 sun-like stars that could be habitable.

“If a planet is far enough away from an M dwarf, it could potentially hold an atmosphere. We cannot yet conclude that all rocky planets around these stars have been reduced to the fate of Mercury,” Hill said. “I remain optimistic.”


Rapid destruction of Earth-like atmospheres by young stars


More information:
Ian JM Crossfield et al, GJ 1252b: Hot Terrestrial Super-Earth with No Atmosphere, Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac886b

Provided by the University of California – Riverside

Quotation: Discovery could significantly narrow the search for space creatures (2022, October 21) Retrieved October 22, 2022 from https://phys.org/news/2022-10-discovery-narrow-space-creatures.html.

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