Revisiting Ulysses electron data with a triple fit of velocity distributions

نویسندگان

چکیده

Given their uniqueness, the Ulysses data can still provide us with valuable new clues about properties of plasma populations in solar wind, and, especially, variations heliographic coordinates. We revisit electron reported by SWOOPS instrument on-board spacecraft between 1990 to early 2008. These observations reveal velocity distributions out thermal equilibrium, anisotropies (e.g., parallel drifts or/and different temperatures, and perpendicular background magnetic field), quasi-thermal suprathermal properties. apply a 2D nonlinear least square fitting procedure, using Levenberg-Marquardt algorithm, simultaneously fit (up few keV) triple model combining three distinct populations: more central core halo, second population consisting mainly strahl (or beaming major field-aligned drift). The recently introduced $\kappa$-cookbook is used describe each component following anisotropic distribution functions (recipes): Maxwellian, regularized kappa-, generalized kappa-distributions. temperature anisotropy quantified best fits considered as case study main parameters characterizing populations. By comparison core, both exhibit higher anisotropies, which slightly increase energy electrons.

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ژورنال

عنوان ژورنال: Astronomy and Astrophysics

سال: 2022

ISSN: ['0004-6361', '1432-0746']

DOI: https://doi.org/10.1051/0004-6361/202243477