Ontdekking kan de zoektocht naar buitenaards leven drastisch versnellen

Rode dwergvlamster (illustratie van de kunstenaar)

Artistieke illustratie van een jonge rode dwerg die de atmosfeer van een planeet weghaalt. Krediet: NASA, ESA en D. Player (STScI)

Planeten die rond het meest voorkomende type ster draaien, zijn mogelijk onbewoonbaar.

Een aardachtige planeet die rond een M-dwerg draait – het meest voorkomende type ster in het universum – lijkt helemaal geen atmosfeer te hebben. Deze dramatische ontdekking zou een grote verschuiving kunnen veroorzaken in de zoektocht naar leven op andere planeten.

Omdat M-dwergen zo gewoon zijn, betekent deze ontdekking dat een groot aantal planeten die om deze sterren draaien ook geen atmosfeer hebben en daarom waarschijnlijk geen levende wezens zullen herbergen.

Het werk dat leidde tot de onthullingen over de geen-atmosfeer[{“ attribute=““>exoplanet, named GJ 1252b, is detailed in a paper that was recently published in The Astrophysical Journal Letters.

This planet orbits its star twice during the course of a single day on Earth and is slightly larger than Earth. It is also much closer to its star than Earth is to the sun, making GJ 1252b intensely hot as well as inhospitable.

“The pressure from the star’s radiation is immense, enough to blow a planet’s atmosphere away,” said Michelle Hill, UC Riverside astrophysicist and study co-author.

Planet Atmosphere Blown Away by Star

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

Earth also loses some of its atmosphere over time because of the sun, but volcanic emissions and other carbon cycling processes make the loss barely noticeable by helping replenish what is lost. However, in greater proximity to a star, a planet cannot keep replenishing the amount being lost.

In our solar system, this is the fate of Mercury. It does have an atmosphere, but one that is extremely thin, made up of atoms blasted off its surface by the sun. The extreme heat of the planet causes these atoms to escape into space.

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 planet’s light, as well as light reflected from its star, is blocked.

The radiation revealed the planet’s scorching daytime temperatures, estimated to reach 2,242 degrees Flaring Red Dwarf Star (Illustration)

Red dwarfs tend to be magnetically active, and erupt with intense flares that could strip a nearby planet’s atmosphere over time, or make the surface inhospitable. Credit:NASA/ESA/STScI/G. Bacon

Even with a tremendous amount of carbon dioxide, which traps heat, the researchers concluded GJ 1252b would still not be able to hold on to an atmosphere. “The planet could have 700 times more carbon than Earth has, and it still wouldn’t have an atmosphere. It would build up initially, but then taper off and erode away,” said Stephen Kane, UCR astrophysicist, and study co-author.

M dwarf stars tend to have more flares and activity than the sun, further reducing the likelihood that planets closely surrounding them could hold on to their atmospheres.

“It’s possible this planet’s condition could be a bad sign for planets even further away from this type of star,” Hill said. “This is something we’ll learn from the

Reference: “GJ 1252b: A Hot Terrestrial Super-Earth with No Atmosphere” by Ian J. M. Crossfield, Matej Malik, Michelle L. Hill, Stephen R. Kane, Bradford Foley, Alex S. Polanski, David Coria, Jonathan Brande, Yanzhe Zhang, Katherine Wienke, Laura Kreidberg, Nicolas B. Cowan, Diana Dragomir, Varoujan Gorjian, Thomas Mikal-Evans, Björn Benneke, Jessie L. Christiansen, Drake Deming and Farisa Y. Morales, 23 September 2022, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ac886b

The research was led by Ian Crossfield at the University of Kansas. It included scientists from UC Riverside as well as

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