Cold planet discovered orbiting ‘nearby’ dwarf star
Barnard’s Star is older than our solar system
An international team of astronomers has detected evidence of a cold planet at least three times the size of Earth orbiting an ancient red dwarf star, right in our stellar neighborhood.
If you were traveling at the speed of light, it would take you just six years to reach it.
In the context of the universe, that’s basically right next door.
The newly discovered world, described Wednesday in Nature, orbits a small, dim star known as Barnard’s Star that is older than our solar system. It takes the planet 233 days to complete a single orbit around its cool red sun.
It is now the second-closest known planet to our solar system.
The only closer known planet is an Earth-sized body that orbits the small red star Proxima Centauri in the Alpha Centauri triple star system. That planet was discovered in 2016 and lies just four light-years from Earth.
The planet around Barnard’s Star is probably too cold to host life, researchers said.
Although it is about as close to its own star as Mercury is to the sun, scientists say it is probably as cold as Saturn. That’s because Barnard’s Star emits only 0.4 percent of the sun’s radiant power.
But the new discovery is exciting for other reasons.
The proximity of the newly found planet to Earth makes it an excellent target for future observations. It is so close that the next generation of telescopes may be able to image it directly, the researchers said.
In addition, the new find provides further evidence that planets are nearly ubiquitous around red dwarf stars, said Ignasi Ribas, an astronomer and director of the Institute of Space Studies of Catalonia in Spain, who led the work.
“The chances of finding new ones is quite high,” he said.
The new detection was made by a team of scientists working on an astronomy collaboration called Red Dots. Together, they are scanning the night sky for planets orbiting nearby dim red dwarf stars. Ultimately they hope to find a world in the habitable zone of these stars, where liquid water could pool on its surface.
Back in the 1960s Peter van de Kamp, a Dutch astronomer, reported the discovery of two planets roughly the size of Jupiter orbiting Barnard’s star.
To come to this conclusion he used a technique called astrometry that measures the movement of a single star across the celestial sphere. The idea is that the gravity of a planet orbiting that star would cause the star to shift its position ever so slightly compared with more distant background stars.
The new discovery of a single, much smaller planet orbiting Barnard’s star is based on a technique called radial velocity, in which scientists use spectrometers to look for a small wobble in the light from the star that would indicate it has a planet orbiting around it.