Sub-hour modulation of non-Io Jovian decametric emission

Abstract

The variability of Jovian decametric emission (DAM), which is not controlled by the Io satellite (non-Io), was studied of timescales of between 1 min and 1 h with DAM records of 1991-2007 from the archive of Nançay Radio Observatory. We found that the internal structure of the non-Io radio storms has the dominating periodicity on of average 21 ± 2 min . This estimate is in close agreement with the periodicity of Io-related emission and with fundamental eigenoscillations of transversal magnetic pulsations in the Io's plasma torus. The average duration of an arc in non-Io DAM dynamic spectra was estimated to be 7.0 ± 0.3 min, although the most probable value was 5.3± 0.7 min, which corresponds to Io-related arcs and 3rd and 4th harmonics of torus proper-oscillations. Our results could be interpreted in terms of electron acceleration in parallel electric fields of standing Alfvén waves generated by Io and trapped in the Io torus. This interpretation agrees with previous arguments that the location of some sources of non-Io emission are in the magnetic shell of the Io plasma torus. However, the aurora component of non-Io DAM is not excluded, since the suggested DAM modulation by the fundamental mode of eigenoscillations inherent in aurora magnetic-lines is undetectable in our analysis because of the short duration of non-Io radio storms.

The Arecibo Detection of the Coolest Radio-Flaring Brown Dwarf

“…Properties of the 4.75 GHz radio emission from J1047+21 are broadly similar to those observed in bursts from other ultracool dwarfs (Berger et al 2001;Hallinan et al 2007Hallinan et al , 2008Berger et al 2009;McLean et al 2011), the Sun (Chernov 2006;White 2007), and the solar system planets (Arkhypov & Rucker 2009;Lamy et al 2010;Mutel et al 2010). A closer examination of sufficiently high signal-to-noise sections of the first two bursts reveals spikes that last no longer than ∼0.5 s. The presence of rapid intensity fluctuations in the data suggests that the shortest observable timescales of these variations may be limited by our 0.1s sampling.…”

New Type of Periodic Bursts of Non-Io Jovian Decametric Radio Emission

“…However, there are studies which suggest also the low-latitude (L < 6) sources. Arkhypov and Rucker [2009] have shown that the periodicity of the non-Io storms coincide with the fundamental eigenmode of the Io torus oscillation and therefore part of the non-Io emission can be directly related to the plasma torus. Therefore one possible source candidate for the energetic particles which may produce the periodic burst of non-Io DAM is the Io plasma torus which consists of highly structured plasma regions.…”

New periodicity in Jovian decametric radio emission

“…However there are several studies which indicate also the existence of a low-latitude (L < 6) component of the non-Io emission, possibly related to the Io torus. Arkhypov and Rucker [2009] have shown that the periodicity of the non-Io storms coincide with the fundamental eigenmode of the Io torus oscillation and therefore part of the non-Io emission can be directly related to the plasma torus.…”