A third of planets circling red dwarf stars in our galaxy ‘could host life’, study claims

Finding life on other planets has long been one of astronomers’ greatest quests.

Now a new study suggests the Milky Way galaxy has hundreds of millions of promising targets to search for signs of life beyond our solar system.

Using NASA’s Kepler telescope, researchers studied a small sample of planets orbiting red dwarfs — low-mass stars common in our galaxy.

They found that one-third of the planets — amounting to hundreds of millions in the Milky Way in total — likely have the right conditions to host life.

The new study was conducted by experts at the University of Florida and published in the journal The Proceedings of the National Academy of Sciences.

“I think this result is very important for the next decade of exoplanet research, as the eyes shift to this population of stars,” said study co-author Sarah Sagear.

“These stars are excellent targets for looking for small planets orbiting where it is possible that water is liquid and therefore the planet is habitable.”

Our Milky Way galaxy is estimated to contain between 100 billion and 400 billion stars – and at least that number of planets.

Interestingly, only about 20 percent of the stars in the Milky Way galaxy resemble our sun, making it a “relative rarity,” according to the researchers.

By far the most common stars are red dwarfs, which are considerably smaller and cooler and have at most half the mass of our sun.

Red dwarfs make up most of the star population in the Milky Way — nearly 75 percent, according to estimates — and are about the size of Jupiter.

For their study, the researchers used new data from NASA’s Kepler telescope, which would capture information about exoplanets as they move in front of their host stars — known as “transiting.” This is an artist’s impression of the Kepler space telescope that was decommissioned by NASA in 2018 after nearly a decade of service

In addition, billions of planets orbit these ordinary dwarf stars in our galaxy, making them a particular target for astronomers.

For their study, the Florida team measured the “eccentricity” of orbits of a sample of more than 150 planets around red dwarf stars in the Milky Way.

To measure the orbits of the planets, the researchers focused mainly on the time it took for the planets to move across the surface of the stars – also known as ‘transiting’.

Their study was also based on new data from the European Space Agency’s Gaia telescope, which has measured the distance to billions of stars in the galaxy.

“The distance is really the most important piece of information that we were missing before, which allows us to do this analysis now,” Sagear said.

To trap enough heat to be habitable, planets must huddle very close to their red dwarf stars, making them susceptible to extreme tidal forces, the astronomers say.

In their analysis based on the telescope data, the team found that two-thirds of the planets around the red dwarf stars could be toasted by these extreme tides, sterilizing them.

But that leaves a third of the planets — which amounts to hundreds of millions in the galaxy — that could be in a “goldilocks” orbit, close enough and soft enough to hold liquid water and possibly host life.

They also found that stars with multiple planets are most likely to have the kind of circular orbits that allow them to hold liquid water.

Meanwhile, stars with only one planet were most likely to see tidal extremes that would sterilize the surface.

The researchers say their findings “have implications for planetary formation and follow-up observations.”

New telescopes like the James Webb will now be the key to identifying water – an important sign of life – on ‘exoplanets’ (planets outside our solar system).