A new Earth-sized exoplanet has been discovered orbiting a dim red star just 219 light-years away. Earth-size doesn’t mean Earth-like, however, as astronomers think the planet could be more similar to Venus than to our cozy world.
In a paper, published in The Astronomical Journal, researchers discuss the discovery of Kepler-1649b. The object has a radius only 8 percent bigger than our own planet and orbits its star in just under nine days.
If it was orbiting anything other than a red dwarf, it would be cinder by now. But the star, Kepler-1649, is smaller and dimmer than the Sun. Its radius is about one-quarter of our star and has a surface temperature of just over 3,200 kelvins (2900°C, 5300°F), significantly lower than the Sun.
While it might not be a molten inferno, the exoplanet is still receiving a huge amount of light – 2.3 times the influx of stellar radiation compared to Earth. Venus gets about 1.9 times more solar flux than we do.
While objects like this might not be life-friendly, studying them is “becoming increasingly important in order to understand the habitable zone boundaries of M dwarfs,” said lead author Isabel Angelo of the SETI Institute in a statement. “There are several factors, like star variability and tidal effects, that make these planets different from Earth-sized planets around Sun-like stars.”
M-dwarfs are one of the most common types of stars in the galaxy, so understanding the regions of habitability around them is very important. The seven-planet star Trappist-1 is an M-dwarf, and astronomers have recently studied the atmosphere of a super-Earth near one of these stars. We might encounter more extreme planets before we find a life-suitable one, however.
“Many people are hung up on finding other Earths. But Venus analogs are just as important,” co-author Elisa Quintana, also at the SETI Institute, said. “Since new telescopes coming down the pike will allow us to probe atmospheres, focusing on both Earth and Venus analogs may help decipher why, in our Solar System, one planet allows life to thrive, and one does not, despite having similar masses, comparable densities, etc.”
The new exoplanet was discovered by the planet-hunting space telescope Kepler. So far, over 4,000 exoplanets have been discovered.