Astronomers at the University of Florida have discovered that hundreds of millions of planets orbiting dwarf stars in the Milky Way could potentially harbor life, occupying a Goldilocks orbit that allows them to resist extreme tidal forces and retain liquid water, according to NASA’s Kepler data. and the Gaia telescopes.

Our familiar warm yellow sun is relatively rare in the Milky Way. Of course, the most common stars are much smaller and cooler, only half the mass of our Sun. Billions of planets orbit these common dwarf stars in our galaxy.

To generate enough heat to be habitable, these planets would have to congregate very close to their minor stars, making them susceptible to extreme tidal forces.

In a new analysis based on the latest data from the telescope, University of Florida astronomers have found that two-thirds of planets around these ubiquitous small stars can be scorched by these extreme tides, sterilizing them. But that leaves a third of the planets that may be orbiting Goldilocks (hundreds of millions in the galaxy) close and soft enough to hold liquid water and possibly harbor life.

UCLA astronomy professor Sarah Ballard and doctoral student Sheila Sager published their findings May 29 in the journalism. Proceedings of the National Academy of Sciences . Ballard and Sager have long studied exoplanets, which are worlds orbiting stars other than the Sun.

“I think this result is really important for the next decade of exoplanet research, because the view is shifting towards this stellar population,” said the city. “These stars are excellent targets for finding minor planets in orbits where the water may be liquid and thus the planet may be habitable.”

Sager and Ballard measured the eccentricity of more than 150 samples of planets around these M dwarf stars, which are about the size of Jupiter. The more oval the orbit, the more eccentric it is. If a planet orbits its star as close as Mercury orbits the Sun, the eccentric orbit can subject it to a process known as tidal heating. The planet flexes and deforms due to the changing gravitational forces in its irregular orbit, while friction heats it up. Ultimately, this could burn the planet, eliminating the possibility of liquid water.

“For these small stars alone, the habitable zone is close enough for these tidal forces to be relevant,” Ballard said. Said.

The data came from NASA’s Kepler telescope, which collects information about exoplanets as they move in front of their stars. Ballard and Sahir focused specifically on how long it takes planets to move across the surface of stars to measure the orbits of planets. Their work also used new data from the Gaia telescope, which measures the distance to billions of stars in the galaxy.

“Distance is a really important piece of information that we missed earlier that allows us to do this analysis now,” said the city. Said.

Sahir and Ballard discovered that stars with multiple planets likely have circular orbits that allow them to hold liquid water. Stars with a single planet were more likely to see extreme tides that could sterilize the surface.

Since a third of the planets in this small sample have orbits soft enough to potentially contain liquid water, this likely means that the Milky Way has hundreds of millions of promising targets for searching for signs of life beyond our solar system.