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Heliosheath magnetic field and plasma observed by Voyager 2 during 2011
Author(s) -
Burlaga L. F.,
Ness N. F.,
Richardson J. D.
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020297
Subject(s) - physics , heliospheric current sheet , magnetic field , amplitude , plasma , log normal distribution , heliosphere , solar wind , astrophysics , interplanetary magnetic field , computational physics , atomic physics , nuclear physics , quantum mechanics , statistics , mathematics
We discuss magnetic field and plasma observations from Voyager 2 (V2) during 2011, when V2 was beginning to see the effects of increasing solar activity following the solar minimum in 2009. The magnetic field strength ( B ) profile showed large amplitude fluctuations that can be resolved into a linear increase of B with time and a sinusoidal variation of the period of 86.2 ± 0.8 days. Voyager 2 was in a unipolar region in which the magnetic polarity was directed away from the Sun along the Parker spiral 96% of the time, indicating that V2 was poleward of the heliospheric current sheet throughout most of 2011. The distribution of B was lognormal, but a Gaussian distribution was observed when the linear variation of B was subtracted from the data. The distribution of daily increments of B was a q ‐Gaussian distribution with q = 1.1 ± 0.1, which is less intermittent than normally observed in the heliosheath. However, the distribution of hourly increments of B was a q ‐Gaussian distribution with q = 1.5 ± 0.03. The density, temperature, and velocity increased linearly from the beginning of 2011 to approximately day 254. The magnetic and thermal pressure tended to increase throughout the year, but the magnetic pressure dominated most of the time. The counting rate of >70 MeV/nucleon particles increased rapidly during the first 250 days, but it leveled out during the rest of the year when B was stronger. The empirical CR‐ B relationship describes this behavior.