[ad_1]
NASA / MIT / TESS
By Daniel Clery
When scientists search for life on distant exoplanets, they usually focus on rocky worlds the size of the Earth. But most of these so-called super-Earths orbit, not yellow dwarfs like our sun, but red dwarfs, whose size is less than 60%. Now, astronomers report that such exoplanets are perhaps not the best places to shelter life for one main reason: they seem to lack habitable atmospheres.
The red dwarfs are by far the most common stars of the Milky Way, but their planets may have trouble staying in an atmosphere, partly because these somewhat erratic stars subject them to powerful streams of radiation.
It is difficult to assess if such planets have an atmosphere, because they are light-years away from Earth – and their light is lost in the glow of their stars. For example, a team of astronomers used NASA's Spitzer Space Telescope 100-hour observation data, which focuses on infrared light, to study LHS 3844b, a nearby exoplanet that is 1.3 times the diameter of Earth.
LHS 3844b (artist's rendition, above) was one of the first planets discovered by NASA's Transiting Exoplanet Survey transiting satellite after its launch in April 2018. At 50 light-years away from the Earth, LHS 3844b is one of the closest exoplanets to Earth. fastest orbits – 11 hours.
The team measured the brightness of the star-planet system when the LHS 3844b shifted to its orbit. From there, they could calculate the brightness of the planet – and therefore its temperature. If LHS 3844b had an atmosphere, weather systems would carry heat around the planet and equalize the temperature distribution. But the team discovered that the planet was extremely hot, directly under the midday sun and close to absolute zero at midnight, suggesting an atmosphere with little or no heat diffusion. Nature aujourd & # 39; hui.
It is only one planet, but the results suggest finding a hospitable planet around a red dwarf might not be as easy as astronomers hoped.
[ad_2]
Source link