Study: One-third of Milky Way Planets May Hold Conditions to Support Life
2023-06-05
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1A new study suggests about one-third of planets orbiting our galaxy's most common stars may hold conditions to support life.
2The study was based on data collected by two telescopes.
3Researchers involved in the study centered their examinations on stars in our Milky Way galaxy known as red dwarfs.
4The American space agency NASA notes that red dwarfs are generally much smaller than our sun.
5They are also the coolest stars and appear more orange than red.
6Red dwarfs are also known as M dwarfs.
7NASA estimates that they make up about 75 percent of all stars in the Milky Way.
8Experts believe billions of planets orbit red dwarf stars.
9The study found that a third of planets orbiting red dwarf stars could be in what scientists call the "habitable zone."
10Being in a star's habitable zone means a planet has temperatures that could permit liquid water to exist on the surface.
11Since water is necessary for life as we know it, the presence of liquid means a planet could possibly support life.
12The planets examined in the study are called exoplanets.
13These are planets that orbit a star other than our sun.
14Sara Ballard, an astronomer at the University of Florida, carried out the research.
15Doctoral student Sheila Sagear helped Ballard on the project.
16Their findings were recently published in Proceedings of the National Academy of Sciences.
17Sagear 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."
18Sagear added that the new findings will be "really important" for additional exoplanet research in the coming years.
19The 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.
20But 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."
21The 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.
22This process is known as tidal heating.
23It can result in planets being "sterilized," with no chance for holding liquid water.
24Sagear and Ballard said they measured the "eccentricity" of more than 150 exoplanets orbiting red dwarf stars.
25They described eccentricity as the shape of the planet's orbit around the star.
26The data came from NASA's Kepler telescope and the European Space Agency's Gaia telescope.
27Instruments helped the team collect data on how often the planets move in front of their stars.
28They also helped the team measure distances between red dwarfs.
29Sagear said the distance measurements were a very important part of the research.
30Past studies had not included such measurements.
31The 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.
32On the other hand, stars with only one planet were most likely to see tidal extremes that could sterilize the surface.
33The 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.
34I'm Bryan Lynn.
1A new study suggests about one-third of planets orbiting our galaxy's most common stars may hold conditions to support life. 2The study was based on data collected by two telescopes. Researchers involved in the study centered their examinations on stars in our Milky Way galaxy known as red dwarfs. 3The American space agency NASA notes that red dwarfs are generally much smaller than our sun. They are also the coolest stars and appear more orange than red. Red dwarfs are also known as M dwarfs. NASA estimates that they make up about 75 percent of all stars in the Milky Way. Experts believe billions of planets orbit red dwarf stars. 4The study found that a third of planets orbiting red dwarf stars could be in what scientists call the "habitable zone." Being in a star's habitable zone means a planet has temperatures that could permit liquid water to exist on the surface. 5Since water is necessary for life as we know it, the presence of liquid means a planet could possibly support life. 6The planets examined in the study are called exoplanets. These are planets that orbit a star other than our sun. 7Sara Ballard, an astronomer at the University of Florida, carried out the research. Doctoral student Sheila Sagear helped Ballard on the project. Their findings were recently published in Proceedings of the National Academy of Sciences. 8Sagear 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." 9Sagear added that the new findings will be "really important" for additional exoplanet research in the coming years. 10The 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. 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." 11The 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. This process is known as tidal heating. It can result in planets being "sterilized," with no chance for holding liquid water. 12Sagear and Ballard said they measured the "eccentricity" of more than 150 exoplanets orbiting red dwarf stars. They described eccentricity as the shape of the planet's orbit around the star. 13The data came from NASA's Kepler telescope and the European Space Agency's Gaia telescope. Instruments helped the team collect data on how often the planets move in front of their stars. They also helped the team measure distances between red dwarfs. 14Sagear said the distance measurements were a very important part of the research. Past studies had not included such measurements. 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. On the other hand, stars with only one planet were most likely to see tidal extremes that could sterilize the surface. 15The 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. 16I'm Bryan Lynn. 17Bryan Lynn wrote this story for VOA Learning English, based on reports from the University of Florida, Proceedings of the National Academy of Sciences and NASA. 18_______________________________________________________________ 19Words in This Story 20galaxy - n. a very large group of stars held together in the universe 21habitable - adj. able to support conditions to support life 22conceivable - adj. possible to imagine or believe 23tidal - adj. relating to the regular rising and falling of the sea 24sterilize - v. to make an area unsuitable to support life 25___________________________________________________________________ 26What do you think of this story? We want to hear from you. We have a new comment system. Here is how it works: 27Each time you return to comment on the Learning English site, you can use your account and see your comments and replies to them. Our comment policy is here.