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“Milky Way's Stars” – Live 17-70 Billion Years: “Best Bet on Planets with Life”

Published on March 7, 2019 "The sun is 10 billion times brighter than an earthly planet around it, so there is much light you must suppress if you want to see an orbiting planet. star may be "just" a billion times brighter than a soil around it, "said Giada Arney of NASA's Goddard Space Flight Center. And they live a very long time &#821 1; 17 billion to 70 billion years, compared to 10 billion years for the sun – which gives plenty of time for life to develop. K-stars also have less extreme activity in their youth than the fog stars of the universe, called M-stars or "red dwarfs". Researchers seeking signs of life beyond our solar system face major challenges, one of which there are hundreds of billions of stars in our galaxy to consider only. To limit the search, they have to figure out: What types of stars are most likely to host habitable planets? A new study finds a particular class of stars called K-stars, which are dimmer than the sun but brighter than the weakest stars, can be particularly promising targets for searching for signs of life. M stars offer some benefits for searching for habitable planets. They are the most common star type in the galaxy, which comprises about 75 percent of all stars in the universe. They are also sparse with their fuel and can shine on for over thirteen years. An example of an M-star, TRAPPIST-1, is known to host seven terrestrial…

Published on March 7, 2019

 The oldest stars of the Milky Way

“The sun is 10 billion times brighter than an earthly planet around it, so there is much light you must suppress if you want to see an orbiting planet. star may be “just” a billion times brighter than a soil around it, “said Giada Arney of NASA’s Goddard Space Flight Center. And they live a very long time &#821

1; 17 billion to 70 billion years, compared to 10 billion years for the sun – which gives plenty of time for life to develop. K-stars also have less extreme activity in their youth than the fog stars of the universe, called M-stars or “red dwarfs”.

Researchers seeking signs of life beyond our solar system face major challenges, one of which there are hundreds of billions of stars in our galaxy to consider only. To limit the search, they have to figure out: What types of stars are most likely to host habitable planets?

A new study finds a particular class of stars called K-stars, which are dimmer than the sun but brighter than the weakest stars, can be particularly promising targets for searching for signs of life.

M stars offer some benefits for searching for habitable planets. They are the most common star type in the galaxy, which comprises about 75 percent of all stars in the universe. They are also sparse with their fuel and can shine on for over thirteen years. An example of an M-star, TRAPPIST-1, is known to host seven terrestrial rocky planets.

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But the turbulent youth of the M-stars present problems for potential life. Stellar flares explosive magnetic energy emissions are much more frequent and energetic from young M-stars than young Sun-like stars. M-stars are also much brighter when they are young, up to a billion years after they are formed, with energy that can boil away oceans on planets that can ever lie in the inhabited zone.

“I think that K stars is in a” sweet spot “between Sun analog stars and M stars,” says Arney, who wanted to find out what biosignatures or signs of life might look like on a hypothetical planet which revolves around a K-star. Her analysis is published in the Astrophysical Journal Letters.

Scientists believe that the simultaneous presence of oxygen and methane in a planet’s atmosphere is a strong biosignature because these gases like to react with each other, destroying each other. So, if you see them present in an atmosphere together, it means something that produces them both quickly, perhaps possibly life, according to Arney.

But since planets around other stars (exoplanet) are so distant, there must be significant amounts of oxygen and methane in an exoplanet’s atmosphere in order to be seen by observers on earth. Arneys analysis showed that the oxygen-methane biosignature is likely to be stronger around a K-star than a solar star.

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Arney used a computer model that simulates chemistry and temperature in a planetary atmosphere and how that atmosphere responds to different host stars. These synthetic atmospheres were then run through a model that simulates the planet’s spectrum to show how it could look like future telescopes.

“When you put the planet around a K-star, the acid does not destroy methane so quickly, so more of it can build up in the atmosphere,” says Arney. “It is because the K-star’s ultraviolet light does not generate high-reactive oxygen gases that destroy methane as easy as a sun-like star. “

This stronger oxygen metering signal has also been predicted for planets around M-stars, but their high activity levels can make M-stars unable to host worthy worlds. K-stars can offer the advantage of a higher probability for simultaneous measurement of oxygen methane compared to sun-like stars without the disadvantages that come with an M-star host

Arneys research also contains discussion about which of the nearby K-stars can be the best targets for future observations. the opportunity to travel to planets around other stars because of their huge distance from us, we are limited to Allight the light from these planets to search for a signal that life can be present. By separating this light into its component colors or spectrum, researchers can identify the constituents of a planet’s atmosphere, as different compounds emit and absorb clear colors.

“I find that some nearby K-stars like 61 Cyg A / B, Epsilon Indi, Groombridge 1618 and HD 156026 may be particularly good targets for future biosignant searches,” says Arney. Center

Picture credit: Westmark stars on the Milky Way galaxy Gabriel Pérez, SMM (IAC)

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