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K2-18b gravitates around a smaller star than the sun, but it is in the "habitable zone" where it is warm enough so that liquid water can exist on its surface. It also receives the same amount of star radiation that the Earth receives from the sun. ( pixabay )
The Hubble Space Telescope data revealed the presence of water vapor in the atmosphere of a planet the size of the Earth outside the solar system.
K2-18b
The exoplanet named K2-18b orbits a smaller star than the sun, but is located in the so-called "habitable zone" where it is hot enough for there to be liquid water at the surface of the planet.
K2-18b is located about 111 light-years away and is nine times more massive than the Earth. Its size makes it an icy giant like Neptune or a rocky world with a thick, hydrogen-rich atmosphere.
Potentially habitable planet
In a study published in the arXiv.org pre-print journal on September 10, researchers revealed that they had detected water vapor in the atmosphere of the planet, making the planet a plausible candidate in the search for extraterrestrial life.
The researchers also said that with its orbit around three cold dwarfs of 33 days, the planet receives roughly the same amount of star radiation that the Earth receives from the sun.
"Thanks to our observations and our climate model of this planet, we have shown that its water vapor can condense into liquid water, which is a first," said Björn Benneke, research scientist at the University of California. 39; Exoplanet Research Institute of the Université de Montréal. ,
Identify planets with water
Researchers can study chemical substances in the atmosphere of planets by observing changes in starlight as planets revolve around their parent stars. Using this method, K2-18b appears to have the molecular signature of water, an essential ingredient of life on Earth.
As the planet transits, the light from its host star shines through the K2-18b atmosphere, but not all stars pass through it. Indeed, the chemical compounds present in the atmosphere absorb the light at indicator frequencies. The water absorbs near infrared light at specific wavelengths and thus creates a visible sign of water vapor.
"We observed eight transits using HST / WFC3 to get the sensitivity needed to detect water vapor," the researchers wrote in their study.
"Our observations demonstrate that state-of-the-art planets provide access to low-mass planets in habitable areas offering the right conditions for liquid water."
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