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Strong hydromagnetic turbulence associated with comet Giacobini‐Zinner
Author(s) -
Tsurutani Bruce T.,
Smith Edward J.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i003p00259
Subject(s) - physics , turbulence , solar wind , comet , instability , ion , astrophysics , plasma , magnetohydrodynamic turbulence , computational physics , atomic physics , magnetohydrodynamics , mechanics , nuclear physics , quantum mechanics
The turbulence surrounding comet Giacobini‐Zinner reached intensities three orders of magnitudes above that of “intermediate” solar wind conditions, was characterized by Δ B/B o almost equal to one, and extended to cometocentric distances beyond 10 6 km. The strong spectral peak at f ∼ 10 −2 Hz and the general intensity profile of the turbulence (a lack of emissions close to the nucleus [< 2.5 × 10 4 km], peak intensities near the bow wave, and a spatial extend > 10 6 km) are in excellent agreement with generation by plasma instabilities associated with the pickup of H 2 O + group ions. The total energy of the magnetic turbulence near f ∼ 10 −2 Hz is estimated to be ∼ 5 × 10 15 joules and that of ion energization due to solar wind pickup ∼6 × 10 13 watts. It thus takes a minimum of ∼ 100 s to build up the magnetic turbulence. This scale is approximately the linear growth rate of the ion pickup instability, giving a consistent picture of the energy source of the turbulence.