Study: One-third of Milky Way Planets May Hold Conditions to Support Life

2023-06-05

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  • A new study suggests about one-third of planets orbiting our galaxy's most common stars may hold conditions to support life.
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  • The study was based on data collected by two telescopes.
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  • Researchers involved in the study centered their examinations on stars in our Milky Way galaxy known as red dwarfs.
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  • The American space agency NASA notes that red dwarfs are generally much smaller than our sun.
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  • They are also the coolest stars and appear more orange than red.
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  • Red dwarfs are also known as M dwarfs.
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  • NASA estimates that they make up about 75 percent of all stars in the Milky Way.
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  • Experts believe billions of planets orbit red dwarf stars.
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  • The study found that a third of planets orbiting red dwarf stars could be in what scientists call the "habitable zone."
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  • Being in a star's habitable zone means a planet has temperatures that could permit liquid water to exist on the surface.
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  • Since water is necessary for life as we know it, the presence of liquid means a planet could possibly support life.
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  • The planets examined in the study are called exoplanets.
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  • These are planets that orbit a star other than our sun.
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  • Sara Ballard, an astronomer at the University of Florida, carried out the research.
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  • Doctoral student Sheila Sagear helped Ballard on the project.
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  • Their findings were recently published in Proceedings of the National Academy of Sciences.
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  • Sagear said in a statement that red dwarfs "are excellent targets to look for small planets in an orbit where it's conceivable that water might be liquid and therefore the planet might be habitable."
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  • Sagear added that the new findings will be "really important" for additional exoplanet research in the coming years.
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  • The researchers said that because dwarf stars are cooler, the exoplanets would have to be very near their star to be warm enough to keep liquid water.
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  • But the researchers also noted that being so close means the planets would also be affected by "extreme tidal forces caused by the star's gravitational effect on the planets."
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  • The researchers said the remaining two-thirds of planets around red dwarf stars have likely been subjected to gravitational forces that cause the planets to heat up.
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  • This process is known as tidal heating.
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  • It can result in planets being "sterilized," with no chance for holding liquid water.
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  • Sagear and Ballard said they measured the "eccentricity" of more than 150 exoplanets orbiting red dwarf stars.
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  • They described eccentricity as the shape of the planet's orbit around the star.
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  • The data came from NASA's Kepler telescope and the European Space Agency's Gaia telescope.
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  • Instruments helped the team collect data on how often the planets move in front of their stars.
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  • They also helped the team measure distances between red dwarfs.
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  • Sagear said the distance measurements were a very important part of the research.
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  • Past studies had not included such measurements.
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  • The team noted that stars with several planets were "most likely to have the kind of circular orbits" that permit them to keep holding liquid water.
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  • On the other hand, stars with only one planet were most likely to see tidal extremes that could sterilize the surface.
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  • The researchers said their results mean that the Milky Way may have hundreds of millions of planets that could be studied for possible signs of life.
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  • I'm Bryan Lynn.