A "Super Earth" – a planet much bigger and colder than our world – has been discovered in orbit around a nearby star, scientists announced in a study published Wednesday.
How big? Over three times the mass of the Earth. How cold? A chilly temperature of about 238 degrees below zero. Super-Earths are planets with masses larger than the Earth, but not as big as the ice giants in our solar system, such as Neptune and Uranus.
The planet and its star are nearby in cosmic terms only: At 30 trillion miles from Earth, Barnard's Star is the closest single star to our solar system. For decades, astronomers have looked for planets around the star.
The newly discovered planet, dubbed Barnard's Star b, is the second-closest known exoplanet to the Earth and orbits the fastest moving star in the night sky. Exoplanets are planets outside of our solar system.
"After a very careful analysis, we are 99 percent confident that the planet is there," said the study's lead scientist, Ignasi Ribas of Spain's Institute of Space Sciences, in a statement.
Data from a worldwide array of telescopes revealed the frozen, dimly lit world. "We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive data sets ever used," Ribas said.
According to the study, the planet lies at a distant region from the star known as the "snow line." This is well beyond the habitable zone in which liquid water, and possibly life, could exist.
“This is an extremely exciting new planet candidate,” Sarah Ballard, an MIT scientist not involved with the research, told Sky and Telescope. However, she cautioned that "I wouldn't buy a ticket to Barnard's Star just yet, knowing that there's a 1 percent chance the planet isn't there.”
The star's nearby status has made it a long-running candidate in the hunt for exoplanets. However, none of the previous searches have led to a discovery.
"This remarkable planet gives us a key piece in the puzzle of planetary formation and evolution," noted Rodrigo Díaz, an astronomer at the University of Buenos Aires in Argentina in an article accompanying the study.
The study was published Wednesday in the peer-reviewed British journal Nature.
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