Researchers have identified four small exoplanets orbiting closely around Barnard's Star. This illustration shows what a planetary system with one of the rocky worlds might look like. (Image credit: International Gemini Observatory/NOIRLab/NSF/AURA/R. Proctor/J. Pollard)
A quartet of Earth-like planets, each about 20 to 30 percent the size of our own, orbit one of our closest stellar neighbors, according to new research. These rocky alien worlds are close enough that future generations of humans could visit them using advanced rocket technology. However, it is unlikely that we will find any life there.
Astronomers have long suspected that Barnard's Star hosts at least one exoplanet — a red dwarf with a mass about one-sixth that of the Sun. At 5.97 light-years from Earth, it is the fourth-closest star to our solar system after the three bound stars of the Alpha Centauri system. (Five potential planets have also been detected around the Alpha Centauri stars, though not all have been confirmed yet.)
Previously, researchers believed that there was a gas giant similar to Jupiter around Barnard's Star, due to the star periodically approaching and moving away from Earth. This indicates that something is gravitationally pulling on the star, similar to how the Moon affects our planet and causes tides. However, the existence of such a planet has not yet been confirmed.
But in a new study published March 11 in The Astrophysical Journal Letters, scientists say they've found that the wobble is caused not by the gravitational pull of a single gas giant, but by the combined influence of four smaller rocky worlds, each about four times more massive than Mercury.
“This is a really exciting find,” said lead author Ritwik Basant, a graduate student at the University of Chicago. “Barnard’s Star is our cosmic neighbor, and yet we know so little about it.”
The combined gravitational forces of four small rocky planets explain the “wobbly” motion of Barnard's Star.
The newly discovered worlds, which have not yet been officially named, “are so close to their host star that they orbit it in a matter of days,” the researchers say. “This likely means that they are too hot to be habitable.”
They also noted that the new results likely rule out the possibility of any other exoplanets existing in the habitable zone of Barnard's Star.
But this does not mean that this system will remain uninhabited forever.
Sourse: www.livescience.com
