Zebra pattern in decametric radio emission of Jupiter

M. Panchenko (1) , S. Rošker (2) , H.O. Rucker (2) , A. Brazhenko , Philippe Zarka (3, 4) , G. Litvinenko (5) , V. E. Shaposhnikov (6) , A.A. Konovalenko (5) , V. Melnik (5) , A.V. Franzuzenko , J. Schiemel (2)

1 IWF - Space Research Institute of Austrian Academy of Sciences
2 Commission for Astronomy of the Austrian Academy of Sciences
3 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
4 USN - Unité Scientifique de la Station de Nançay
5 IRA - Institute of Radio Astronomy of NAS of Ukraine
6 Institute of Applied Physics of RAS

We report the systematic analysis of zebra-like fine spectral structures in decametric frequency range of Jovian radio emission. Observations were performed by the large ground-based radio telescope URAN-2 during three observation campaigns between, Sep., 2012, and May, 2015. In total, 51 zebra pattern (ZP) events were detected. These rare fine radio features are observed in frequency range from 12.5 to 29.7 MHz as quasi-harmonically related bands of enhanced brightness. ZPs are strongly polarized radio emission with a duration from 20 s to 290 s and flux densities similar to 10(5)-10(6) Jy (normalized to 1 AU), that is, 1-2 orders lower than for Io-decametric radio emission (DAM). Occurrence of the events does not depend on the position of Io satellite but is strongly controlled by the Jovian central meridian longitude (CML). ZPs are mainly detected in two active sectors of Jovian CMLs: 100 degrees to 160 degrees for Northern sources (right-handed polarized) and 300 degrees and 60 degrees (via 360 degrees) for the Southern sources (left-handed). The frequency interval between neighboring stripes is from 0.26 to 1.5 MHz and in most cases this interval increases with frequency. We discussed the double plasma resonance with electrons or ions as a possible source of the ZPs. The performed analysis of the observations allows us to conclude that the observed ZPs are a new type of narrow band spectral structures in the Jovian DAM.

Mots clés: planets and satellites: individual: Jupiter; instabilities; waves; radiation mechanisms: non-thermal; radio continuum: planetary systems

Domaines: Astrophysique [astro-ph]; Physique de l'espace [physics.space-ph]

M. Panchenko, S. Rošker, H.O. Rucker, A. Brazhenko, Philippe Zarka, et al.. Zebra pattern in decametric radio emission of Jupiter. Astronomy and Astrophysics - A&A, 2018, 610, pp.A69. ⟨10.1051/0004-6361/201731369⟩. ⟨insu-01970017⟩