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ATLANTA — Two astronomers in Georgia State’s Department of Physics & Astronomy have created a roadmap that could help scientists find life on other planets by studying the most common stars in the universe.
Called M dwarf stars, these bodies make up roughly three-fourths of the stars in the universe, even though none can be seen with the naked eye.
“I think nearly all types of stars could support life,” said Wei-Chun Jao, staff astronomer and adjunct professor at Georgia State University. “But M dwarfs offer astronomers the most opportunities to find it.”
Distinguished University Professor Todd Henry believes that between 50 to 100 percent of M dwarfs could harbor planets, even though astronomers have identified planets orbiting just 3 percent of this kind of star. Some of the orbiting planets may support life.
“I like to poke at my friends who look for planets as a full-time job,” Henry said. “I say, “What have you guys been doing?’”
Henry and Jao have recently published a paper in the Annual Review of Astronomy and Astrophysics titled “The Character of M Dwarfs,” which they say not only collects current research on these stars but also points the way for scientists to find planets that support life.
“Life-supporting planets that orbit stars other than the Sun, which astronomers call exoplanets, is new territory,” Henry said.
Henry added that M dwarfs offer the best chance for scientists to find habitable exoplanets because they have the most “real estate”— the largest accumulated space where the temperature is right for liquid water, a key ingredient for life on Earth.
“The best solution,” Jao said, “is to study them all whenever we can.”
Henry and Jao’s paper describes the many details of M dwarf stars and provides a list of the closest stars with reported planets, including planets that fall into liquid water zones.
Henry and Jao said astronomers can now search for evidence of life with a better understanding of the stars that dominate the population around our Sun and there is less guesswork about what types of planets may be found orbiting them.
Henry and Jao said the key to finding life on another planet is identifying the right molecules in its atmosphere. Water or methane can offer important clues, but finding evidence of oxygen or ozone would be especially promising.
“If you see either in an atmosphere, something is creating the molecules now, and life such as plants that manufacture oxygen is a likely cause,” Henry said.
These molecules can be found with instruments onboard the James Webb and Nancy Roman Space Telescopes.
“The Characteristics of M Dwarfs” was published in the Annual Review of Astronomy and Astrophysics in September 2024. To view the article, click here.
—Story by William Greer