14 DAY TRIAL // Astronomers believe they may have found signs of a stealthy extrasolar planet around the star Kepler-19, which is located about 650 light-years away. An exoplanet is already known to orbit this star, but the team says that a second one may also lurk, undetected as of yet.
The group arrived at this conclusion after analyzing the orbit of the exoplanet Kepler-19b in great detail. Experts observed slight variations in the time the object takes to complete a round trip around its parent star, which are very unusual for such large bodies.
At times, the exoplanet is five minutes early to complete a full orbit, while on other occasions it arrives five minutes late. While this may not be a lot of time for humans, it certainly represents a significant change for celestial mechanics.
What this study suggests is that a second exoplanet exists in the Kepler-19 system that exerts a significant gravitational pull on the known planet. This is the only thing astronomers could think of to explain what they are seeing.
According to scientists operating the NASA Kepler planet-hunting telescopes, one of the most efficient instruments for detecting new worlds, discovering the potential existence of Kepler-19c would have been impossible through radial velocity or transit methods.
“This invisible planet makes itself known by its influence on the planet we can see. 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 them when you get outside,” scientist Sarah Ballard explains.
The expert, who is based at the Harvard-Smithsonian Center for Astrophysics (CfA), is the lead author of the new research. Details of the work have already been accepted for publication in an upcoming issue of the esteemed Astrophysical Journal.
Interestingly enough, about the same study method was used to discover Neptune. At the time, astronomers noticed variations in the orbit of Uranus, and inferred the existence of a large body capable of exerting a massive gravitational pull beyond its orbit.
What astronomers want to do now is use this approach as a method for detecting other exoplanets as well. “This method holds great promise for finding planets that can't be found otherwise,” CfA astronomer and study coauthor David Charbonneau explains.
The orbit of the newly-found exoplanet may be tilted in respect to that of its companion. At the same time, its mass is not large enough to pull on the parent star in a considerable manner, which also implies that it could be a rocky world.
“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,” University of California in Santa Cruz (UCSC) expert and study coauthor Daniel Fabrycky concludes.