Volume 552, April 2013
|Number of page(s)||6|
|Section||Planets and planetary systems|
|Published online||26 March 2013|
Hint of 150 MHz radio emission from the Neptune-mass extrasolar transiting planet HAT-P-11b ⋆
1 CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
2 UPMC Univ. Paris 6, UMR 7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
3 National Centre for Radio Astrophysics, TIFR, Post Bag 3, Pune University Campus, Pune 411007, India
4 LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
Received: 11 June 2012
Accepted: 15 February 2013
Since the radio-frequency emission from planets is expected to be strongly influenced by their interaction with the magnetic field and corona of the host star, the physics of this process can be effectively constrained by making sensitive measurements of the planetary radio emission. Up to now, however, numerous searches for radio emission from extrasolar planets at radio wavelengths have only yielded negative results. Here we report deep radio observations of the nearby Neptune-mass extrasolar transiting planet HAT-P-11b at 150 MHz, using the Giant Meterwave Radio Telescope (GMRT). On July 16, 2009, we detected a 3σ emission whose light curve is consistent with an eclipse when the planet passed behind the star. This emission is at a position 14′′ from the transiting exoplanet’s coordinates; thus, with a synthetized beam of FWHM ~ 16′′, the position uncertainty of this weak radio signal encompasses the location of HAT-P-11. We estimate a 5% false positive probability that the observed radio light curve mimics the planet’s eclipse light curve. If the faint signature is indeed a radio eclipse event associated with the planet, then its flux would be 3.87 mJy ± 1.29 mJy at 150 MHz. However, our equally sensitive repeat observations of the system on November 17, 2010 did not detect a significant signal in the radio light curve near the same position. This lack of confirmation leaves us with the possibility of either a variable planetary emission, or a chance occurrence of a false positive signal in our first observation. Deeper observations are required to confirm this hint of 150 MHz radio emission from HAT-P-11b.
Key words: planetary systems / stars: coronae / techniques: interferometric
Data for these observations can be retrieved electronically from the GMRT archive server http://ncra.tifr.res.in/~gmrtarchive and by request to firstname.lastname@example.org
© ESO, 2013
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