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The search for life in the Universe may be more difficult than previously thought: a new study has found that planets around the most common stars in space likely lost their habitable conditions during their formation, SciTechDaily reports.
Scientists at the University of Washington have found that planets in the habitable zone of M dwarfs — stars smaller and dimmer than the Sun — could experience such intense heat that their oceans and atmospheres have evaporated. The situation is complicated by the fact that the habitable zone around these stars is located very close to them.
The critical factor was the early period of M dwarfs' existence, when they go through a phase of extreme brightness lasting hundreds of millions of years. During this time, the surface temperatures of the planets can exceed 1000 °C, leading to complete evaporation of water and the formation of a thick atmosphere of water vapor.
An additional threat is the powerful ultraviolet and X-ray radiation from M dwarfs. It can split water molecules into oxygen and hydrogen, with the lighter hydrogen escaping the atmosphere and the oxygen accumulating. The result can be an atmosphere 10 times denser than Venus's.
This discovery has significant implications for the search for extraterrestrial life. The presence of oxygen in a planet's atmosphere has traditionally been considered a possible sign of life, but the study shows that on planets near M-dwarfs, it can appear naturally, without the involvement of living organisms.
Such planets have been dubbed "Mirage Earths" because of their deceptive resemblance to Earth in the complete absence of water. Observations using modern telescopes, including the James Webb, will help confirm or refute this hypothesis.
The search for life in the Universe may be more difficult than previously thought: a new study has found that planets around the most common stars in space likely lost their habitable conditions during their formation, SciTechDaily reports.
Scientists at the University of Washington have found that planets in the habitable zone of M dwarfs — stars smaller and dimmer than the Sun — could experience such intense heat that their oceans and atmospheres have evaporated. The situation is complicated by the fact that the habitable zone around these stars is located very close to them.
The critical factor was the early period of M dwarfs' existence, when they go through a phase of extreme brightness lasting hundreds of millions of years. During this time, the surface temperatures of the planets can exceed 1000 °C, leading to complete evaporation of water and the formation of a thick atmosphere of water vapor.
An additional threat is the powerful ultraviolet and X-ray radiation from M dwarfs. It can split water molecules into oxygen and hydrogen, with the lighter hydrogen escaping the atmosphere and the oxygen accumulating. The result can be an atmosphere 10 times denser than Venus's.
This discovery has significant implications for the search for extraterrestrial life. The presence of oxygen in a planet's atmosphere has traditionally been considered a possible sign of life, but the study shows that on planets near M-dwarfs, it can appear naturally, without the involvement of living organisms.
Such planets have been dubbed "Mirage Earths" because of their deceptive resemblance to Earth in the complete absence of water. Observations using modern telescopes, including the James Webb, will help confirm or refute this hypothesis.
