A third of small M dwarf stars can support life, according to a new analysis of Kepler data. Although the sun is a typical star, it is not the only type of star that exists. The majority of stars in our galaxy are M dwarfs (also known as red dwarfs), which are much smaller and redder than the sun. According to recent findings, many of these stars may have the capacity to support life.
There are hundreds of millions of habitable planets in the Milky Way alone, and a third of the planets surrounding M dwarfs may be suitable for life, according to a new analysis of data from the planet-hunting Kepler spacecraft.
University of Florida astronomers developed measurements of exoplanet orbits using new data from the European Space Agency's Gaia satellite, which precisely analyzes the distances and motions of stars. The eccentricity of each orbit, a measure of how spread out the planet's course around its star was, was a variable the researchers wanted to determine.
Sheila Sagear, the study's lead author and a doctoral student in astronomy at the University of Florida, said in a statement: "Distance is indeed the most important piece of information that we missed before and now allows us to do this analysis."
In a process known as tidal warming, planets around M dwarfs with large eccentricities (very long, oval orbits) are scorched by the star if they are close enough. The planet's eccentric orbit causes stretching and compression from the star's gravitational pull, resulting in tidal heating. All this movement creates heat from friction, just like when you rub your hands together. If a planet gets too hot, it loses its water and ability to support life on its surface.
If a planet orbiting an M dwarf were further away, tidal warming might not be an issue, but the planet would be too cold and lacking the warmth necessary for life. Therefore, exoplanets orbiting M dwarfs need to be close to their stars to be far from likely to be hot enough for life, putting them at risk of tidal heating if their orbits are not a perfect circle.
According to Sarah Ballard, an astronomer at the University of Florida and co-author of the study, the habitable zone is close enough to these small stars for these tidal forces to be significant.
What's in the Goldilocks Area?
Sagear and Ballard determined that two-thirds of the planets surrounding M dwarfs would be ripped apart by the heat of their host stars, eliminating any chance of habitability. This was based on new and improved findings for a number of exoplanets discovered by the Kepler satellite observatory. But it still leaves a third of the planets in the "Goldilocks" region, where liquid water and the possibility of life could theoretically coexist. If a planet has an exoplanet companion orbiting the same star, it is also more likely to have a stable, circular orbit in the Goldilocks region.
"I think this result is really important for the next decade of exoplanet research," said Sagear, as attention turned to this stellar population. These stars are great places to look for minor planets in orbits where it's possible to find liquid water that would make the planet potentially habitable.
📩 02/06/2023 10:15