February 15, 2014
Kepler 413-b with its out-of-alignment orbit around two dwarfs. Image Credit: NASA, ESA, and A. Feild (STScI)
Kepler space telescope keeps us intrigued with strange new exoplanets that it discovers on regular basis, but the latest discovery of Kepler 413-b, a wobbly planet with a wobbly, out-of-alignment orbit could indicate that the majority of exoplanets is even harder to detect than previously thought.
Planet-hunting space telescope Kepler detects exoplanets by observing regular drops in star's luminosity which indicates there's another body, a planet, passing in front of the star, from our point of view.
One of the most recent such discovery is an exoplanet designated Kepler 413-b. It orbits a pair of orange and red dwarf stars in the constellation Cygnus. It takes 66 days for the planet to complete a full orbit, which means that every 66 days Kepler detects a drop in light emitted from the two dwarfs.
Or rather it would detect it if the planet's orbit were in alignment with two stars.
"Looking at the Kepler data over the course of 1,500 days, we saw three transits in the first 180 days – one transit every 66 days – then we had 800 days with no transits at all. After that, we saw five more transits in a row," said Veselin Kostov, John Hopkins University, Baltimore, USA. He is the principal investigator on the observation. The next transit of the planet visible from Earth is predicted to occur in 2020.
This wobbling of the planet's orbit could be caused by either other planets in the system or another star gravitationally bound to the system.
"Presumably there are planets out there like this one that we're not seeing because we're in the unfavorable period," said Peter McCullough, Kostov's colleague from Johns Hopkins University. "And that's one of the things that Veselin is researching: Is there a silent majority of things that we're not seeing?"
If the majority of exoplanets indeed have wobbly orbits, it would be harder to detect them with Kepler space telescope, but not impossible. Also, there are other method for planet detection, such as observing the way the planet is pulling the star. It would also indicate that there is more planets in our galaxy than we currently suspect.
Interesting about Kepler 413-b is that not only does its orbit wobble, the planet itself wobbles on its spin axis. It does so at an extreme rate by varying 30 degrees every 11 years. In comparison, Earth's axial inclination is 23.5 degrees, but it takes almost 26,000 years for one cycle, making it very stable compared to Kepler 413-b.