Universität zu Köln

Bourouaine, S., Marsch, E. and Neubauer, F. M. (2011). Temperature anisotropy and differential streaming of solar wind ions. Correlations with transverse fluctuations. Astron. Astrophys., 536. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 0004-6361

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Abstract

We study correlations of the temperature ratio (which is an indicator for perpendicular ion heating) and the differential flow of the alpha particles with the power of transverse fluctuations that have wave numbers between 0.01 and 0.1 (normalized to k(p) = 1/lp, where l(p) is the proton inertial length). We found that both the normalized differential ion speed, V-alpha p/V-A (where V-A is the Alfven speed) and the proton temperature anisotropy, T-perpendicular to p/T-parallel to p, increase when the relative wave power is growing. Furthermore, if the normalized differential ion speed stays below 0.5, the alpha- particle temperature anisotropy, T-perpendicular to alpha/T-parallel to alpha, correlates positively with the relative power of the transverse fluctuations. However, if V-alpha p/V-A is higher than 0.6, then the alpha- particle temperature anisotropy tends to become lower and attain even values below unity despite the presence of transverse fluctuations of relatively high amplitudes. Our findings appear to be consistent with the expectations from kinetic theory for the resonant interaction of the ions with Alfven/ion-cyclotron waves and the resulting wave dissipation.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bourouaine, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Marsch, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Neubauer, F. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-483779
DOI:	10.1051/0004-6361/201117866
Journal or Publication Title:	Astron. Astrophys.
Volume:	536
Date:	2011
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	0004-6361
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CORONAL HOLES; WAVES; CYCLOTRON; ACCELERATION; COLLISIONS; TURBULENCE; PROTONS Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48377