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Are periodic solar wind number density structures formed in the solar corona?
Author(s) -
Viall Nicholeen M.,
Spence Harlan E.,
Kasper Justin
Publication year - 2009
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 - 10.1029/2009gl041191
Subject(s) - solar wind , coronal mass ejection , corona (planetary geology) , physics , solar cycle 22 , nanoflares , coronal hole , solar physics , interplanetary spaceflight , coronal loop , astrophysics , interplanetary medium , solar maximum , solar cycle , solar minimum , atmospheric sciences , astronomy , plasma , astrobiology , quantum mechanics , venus
We present an analysis of the alpha to proton solar wind abundance ratio (A He ) during a period characterized by significant large size scale density fluctuations, focusing on an event in which the proton and alpha enhancements are anti‐correlated. In a recent study using 11 years (1995–2005) of solar wind observations from the Wind spacecraft, N. M. Viall et al. [2008] showed that periodic proton density structures occurred at particular radial length‐scales more often than others. The source of these periodic density structures is a significant and outstanding question. Are they generated in the interplanetary medium, or are they a relic of coronal activity as the solar wind was formed? We use A He to answer this question, as solar wind elemental abundance ratios are not expected to change during transit. For this event, the anti‐phase nature of the A He variations strongly suggests that periodic solar wind density structures originate in the solar corona.