Invisible alien planet Kepler-19b and
For the first time,
scientists claim to have definitively discovered an "invisible" alien
planet whose gravity affects the orbit of another neighboring planet.
Both the planets, known as Kepler-19b and Kepler-19c, were detected by
NASA's Kepler space telescope which was launched in 2009 with an aim to hunt for alien worlds.
First, Kepler spotted 19b as it passed in front of, or transited, its
host star. Then, scientists inferred the existence of 19c after observing that 19b's transits periodically came a little later or
earlier than expected. The gravity of 19c tugs on 19b, changing its orbit.
Invisible alien planet discovered
The discovery of Kepler-19c, the researchers said, marks the first time
this method, known as transit timing variation or TTV, has robustly found an
exoplanet. "My expectation is that this method will be applied dozens of times, if
not more, for other candidates in the Kepler mission," said lead researcher Sarah Ballard of the Harvard-Smithsonian Centre for
Astrophysics in Cambridge, Massachusetts.
The Kepler spacecraft typically hunts for alien worlds by measuring the
telltale dips in a star's brightness caused when a planet crosses the
star's face from the telescope's perspective, blocking some of its light.
It has been incredibly successful using this so-called transit method,
spotting 1,235 candidate alien planets in its first four months of
operation. That's the way it detected Kepler-19b -- a world 650 light-years away from Earth in the constellation Lyra.
Invisible alien planet 2.2 times that of
The researchers, who reported their findings in The Astrophysical
Journal, said Kepler-19b has a diameter about 2.2 times that of Earth,
and orbits 13.5 million km from its parent star.
It likely has a surface
temperature around 900 degrees Fahrenheit (482 degrees Celsius). Kepler-19b transits its host star once every nine days and seven hours.
But that number isn't constant, Ballard and her team found; transits can
occur up to five minutes early or five minutes late.
That variation told them another planet was tugging on 19b, alternately
speeding it up and slowing it down. Researchers know little about
Kepler-19c at the moment. It takes the alien world 160 days or less to
zip around its host star, and 19c's mass could range from a few times
that of Earth to six times that of Jupiter, the researchers said. But 19c should start coming into clearer focus soon.
"It's a mystery world, but of course we don't expect it to remain a
mystery," study co-author David Charbonneau, also of the Harvard-Smithsonian Center for Astrophysics, said.
"Kepler, and large ground-based telescopes, should help us figure out
its true identity soon enough!"