NAM 08: Astronomers can tune in to radio auroras to find exoplanets
Detecting exoplanets that orbit at large distances from their star remains a challenge for planet hunters. Now, scientists at the University of Leicester have shown that emissions from the radio aurora of planets like Jupiter should be detectable by radio telescopes such as LOFAR, which will be completed later this year. Dr Jonathan Nichols will present results at the RAS National Astronomy Meeting in Llandudno, Wales, on Monday 18th April.
"This is the first study to predict the radio emissions by exoplanetary systems similar to those we find at Jupiter or Saturn. At both planets, we see radio waves associated with auroras generated by interactions with ionised gas escaping from the volcanic moons, Io and Enceladus. Our study shows that we could detect emissions from radio auroras from Jupiter-like systems orbiting at distances as far out as Pluto," said Nichols.
Of the hundreds of exoplanets that have been detected to date, less than 10% orbit at distances where we find the outer planets in our own Solar System. Most exoplanets have been found by the transit method, which detects a dimming in light as a planet moves in front of a star, or by looking for a wobble as a star is tugged by the gravity of an orbiting planet. With both these techniques, it is easiest to detect planets close in to the star and moving very quickly.
"Jupiter and Saturn take 12 and 30 years respectively to orbit the Sun, so you would have to be incredibly lucky or look for a very long time to spot them by a transit or a wobble," said Dr Nichols.
Dr Nichols examined how the radio emissions for Jupiter-like exoplanets would be affected by the rotation rate of the planet, the rate of plasma outflow from a moon, the orbital distance of the planet and the ultraviolet (UV) brightness of the parent star. He found that, in many scenarios, exoplanets orbiting UV-bright stars between 1 and 50 Astronomical Units (AU) would generate enough radio power to be detectable from Earth. For the brightest stars and fastest spinning planets, the emissions would be detectable from systems 150 light years away from Earth.
"In our Solar System, we have a stable system with outer gas giants and inner terrestrial planets, like Earth, where life has been able to evolve. Being able to detect Jupiter-like planets may help us find planetary systems like our own, with other planets that are capable of supporting life," said Dr Nichols.
Dr Jonathan Nichols
University of Leicester
On Monday 18th April, Dr Nichols will be contactable through the NAM2011 Press Office.
NAM 2011 Press Office (0900 – 1730 BST, 18-21 April only)
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Dr Robert Massey
Royal Astronomical Society
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Royal Astronomical Society
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Images can be found at: http://www.ion.le.ac.uk/~jdn/images.html
The results have been accepted for publication in the Monthly Notices of the Royal Astronomical Society:
'Magnetosphere-ionosphere coupling at Jupiter-like exoplanets with internal plasma sources: implications for detectability of auroral radio emissions' by J.D Nichols
NOTES FOR EDITORS
1 AU is 149 598 000 kilometres, the distance between the Earth and the Sun.
Bringing together around 500 astronomers and space scientists, the RAS National Astronomy Meeting 2011 (NAM 2011: http://www.ras.org.uk/nam-2011) will take place from 17-21 April in Venue Cymru (http://www.venuecymru.co.uk), Llandudno, Wales. The conference is held in conjunction with the UK Solar Physics (UKSP: http://www.uksolphys.org) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST: http://www.mist.ac.uk) meetings. NAM 2011 is principally sponsored by the RAS and the Science and Technology Facilities Council (STFC: http://www.stfc.ac.uk).
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The Royal Astronomical Society (RAS: http://www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
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The Science and Technology Facilities Council (STFC: http://www.stfc.ac.uk) ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange. The Council has a broad science portfolio including Astronomy, Particle Astrophysics and Space Science. In the area of astronomy it funds the UK membership of international bodies such as the European Southern Observatory.
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