doi:10.1038/nindia.2013.50 Published online 8 April 2013
Using a ground-based radio telescope, researchers have captured faint variable radio emissions from an extrasolar planet, orbiting a metal-rich star about 125 light years from the Earth1 . Known as HAT-P-11b, this planet is 26 times heavier than the Earth. Such radio emissions will be useful in the search for similar extrasolar planets.
Radio emissions from extrasolar planets can reach nearly 100,000 times the radio output from planets like Jupiter. Earth-bound radio telescopes can 'listen' to such radio flares. However, no previous studies had used such telescopes to eavesdrop on radio signals emanating from distant extrasolar planets.
To detect radio signals from the extrasolar planet, the researchers used the Giant Metrewave Radio Telescope installed near Pune. They tuned the telescope to a specific radio frequency of the extrasolar planet. The planet is eclipsed by its host star for about two hours when it revolves around the star. The planet's eclipses can be used to discriminate any planetary emission from the host star's emission.
The researchers detected faint radio emission in the first phase of observations. No emission was detected when the planet was eclipsed by the host star. No radio emission was observed during the second phase of observations made more than a year after the first one.
The planet HAT-P-11b has a stronger magnetic field than Jupiter. With a high abundance of heavy elements, short orbital period and a large core mass, this planet differs from all the planets in our solar system. The researchers say that the hint of radio emissions identifies HAT-P-11 b as a prime candidate for many follow-up observations in the near future.