Astronomers believe that they have found an invisible world after detecting a planet, which revolves around its orbit in irregular intervals.
Nasa’s Kepler spacecraft has spotted a planet that alternately runs late and early in its orbit because a second, “invisible” world is tugging on it.
This is the first definite detection of a previously unknown planet using this method. No other technique could have found the unseen companion.
“This invisible planet makes itself known by its influence on the planet we can see,” said astronomer Sarah Ballard of the Harvard-Smithsonian Centre for Astrophysics (CfA), who is the lead author on the study.
“It’s like having someone play a prank on you by ringing your doorbell and running away. You know someone was there, even if you don’t see anyone when you get outside,” she added.
Both the seen and unseen worlds orbit the Sun-like star Kepler-19, which is located 650 light-years from Earth in the constellation Lyra.
So far, astronomers don’t know anything about the invisible world Kepler-19c, other than that it exists.
It weighs too little to gravitationally tug the star enough for them to measure its mass. And Kepler hasn’t detected it transiting the star, suggesting that its orbit is tilted relative to Kepler-19b.
“Kepler-19c has multiple personalities consistent with our data. For instance, it could be a rocky planet on a circular 5-day orbit, or a gas-giant planet on an oblong 100-day orbit,” said co-author Daniel Fabrycky of the University of California, Santa Cruz (UCSC).
The study will be published in The Astrophysical Journal.