Astronomers can tune in to radio auroras to find exoplanets

Posted by pt91 at Apr 19, 2011 10:45 AM |
Radio telescopes could be used for planet-hunting, according to University of Leicester researchers
Astronomers can tune in to radio auroras to find exoplanets

This unique Hubble image from early 2009 features Saturn with the rings edge-on and both poles in view, offering a stunning double view of its fluttering aurorae. Credit: NASA, ESA and Jonathan Nichols (University of Leicester)

Issued by the Royal Astronomical Society on 18 April 2011

Images available via http://www.ion.le.ac.uk/~jdn/images.html

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 presented 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 ionized 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.

Media Contacts:

Dr. Robert Massey

Royal Astronomical Society

rm@ras.org.uk

Anita Heward

Royal Astronomical Society

anitaheward@btinternet.com

NAM 2011 Press Office:

(09:00-17:30 BST, 18-21 April only)

Conwy Room, Venue Cymru, Llandudno, Wales

+44 (0)1492 873 637, +44 (0)1492 873 638

Science Contact:

Dr. Jonathan Nichols

University of Leicester

jdn@ion.le.ac.uk

On Monday 18th April, Dr. Nichols will be contactable through the NAM 2011 Press Office.

Images:

http://www.ion.le.ac.uk/~jdn/images.html

Further Information

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.

1 AU is 149,598,000 kilometers, the average distance between the Earth and the Sun.

NAM 2011

Bringing together around 500 astronomers and space scientists, the RAS National Astronomy Meeting 2011 (NAM 2011:

http://www.ras.org.uk/nam-2011) takes place from 17 to 21 April in Venue Cymru (http://www.venuecymru.co.uk), Llandudno, Wales. The conference is held in conjunction with the U.K. 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).

The Royal Astronomical Society

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 U.K. astronomy nationally and internationally. Its more than 3,500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories, and laboratories as well as historians of astronomy and others.

The Science and Technology Facilities Council

The Science and Technology Facilities Council (STFC:

http://www.stfc.ac.uk) ensures the U.K. 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 U.K. membership of international bodies such as the European Southern Observatory.

Venue Cymru

Venue Cymru (http://www.venuecymru.co.uk) is a purpose-built conference center and theater with modern facilities for up to 2,000 delegates. Located on the Llandudno promenade with stunning sea and mountain views, Venue Cymru comprises a stunning location, outstanding quality, and exceptional value: the perfect conference package.

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