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By Steve Gorman
(Reuters) – Direct observations from a NASA space telescope for the first time revealed the atmospheric void of a rocky, Earth-sized world beyond our own solar system orbiting the most common type of star in the galaxy, according to a study released on Monday.
The research, published in the scientific journal Nature, also shows the distant planet's surface is likely to resemble the barren of the Earth's moon or Mercury, possibly covered in dark volcanic rock.
The planet lies about 48.6 light years from Earth and is one of more than 4,000 so-called exoplanets identified over the past two decades in distant milky way.
Known to astronomers as LHS 3844b, this exoplanet about 1.3 times the size of Earth is locked in a tight orbit – one revolution every 11 hours – a small, relatively cool star called a red dwarf, the most prevalent and long-lived type of star in the galaxy.
The planet's lack of atmosphere is probably due to intense radiation from its parent red dwarf, which, though dim by stellar standards, also emits high levels of ultraviolet light, the study says.
The study will likely add to a debate among astronomers about the search for life-sustaining conditions beyond our solar system should focus on exoplanets around red dwarfs – accounting for 75% of all stars in the Milky Way – or less common, larger, hotter stars more like our own sun.
The main finding is that it is likely to be achieved by the temperature difference between the side of the planet and its face, and the cooler, dark side facing away from it.
A negligible amount of heat between the two sides indicates a lack of winds that would otherwise be present to transfer warmth around the planet.
"The temperature contrasts on this planet is as big as it can possibly be," said researcher Laura Kreidberg of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. She is the lead author of the study.
Similar analysis, formerly known as exoplanet, 55 Cancri This exoplanet, unlike LHS 3844b, orbits a sun-like star.
NASA's newly launched Transiting Exoplanet Survey Satellite, an orbiting telescope that pinpoints remote worlds by spotting periodic, dips into the light of their parent stars when an object passes in front of them.
But it was followed-up observations from another orbiting instrument, the Spitzer Space Telescope, which can detect infrared light directly from an exoplanet, that provided new insights about its features.
(Reporting by Steve Gorman in Los Angeles, Editing by Bill Tarrant and Lisa Shumaker)
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