ALFVEN-WAVE TURBULENCE AND PERPENDICULAR ION TEMPERATURES IN CORONAL HOLES

Journal Article · Wed Sep 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/720/1/548· OSTI ID:21460133

Chandran, Benjamin D. G., ^[1]

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1. Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)

Low-frequency Alfven-wave turbulence causes ion trajectories to become chaotic, or 'stochastic', when the turbulence amplitude is sufficiently large. Stochastic orbits enable ions to absorb energy from the turbulence, increasing the perpendicular ion temperature T{sub perpendiculari} even when the fluctuation frequencies are too small for a cyclotron resonance to occur. In this paper, an analytic expression for the stochastic heating rate is used in conjunction with an observationally constrained turbulence model to obtain an analytic formula for T{sub perpendiculari} as a function of heliocentric distance r, ion mass, and ion charge in coronal holes at 2 R{sub sun} {approx}< r {approx}< 15 R{sub sun}. The resulting temperature profiles provide a good fit to observations of protons and O{sup +5} ions at 2 R {sub sun} {approx}< r {approx}< 3 R{sub sun} from the Ultraviolet Coronagraph Spectrometer (UVCS). Stochastic heating also offers a natural explanation for several detailed features of the UVCS observations, including the preferential and anisotropic heating of minor ions, the rapid radial increase in the O{sup +5} temperature between 1.6 R{sub sun} and 1.9 R{sub sun}, and the abrupt flattening of the O{sup +5} temperature profile as r increases above 1.9 R{sub sun}.

• OSTI ID: 21460133
• Journal Information: Astrophysical Journal, Vol. 720, Issue 1; Other Information: DOI: 10.1088/0004-637X/720/1/548; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ALFVEN WAVES
CHAOS THEORY
ION TEMPERATURE
MAGNETOHYDRODYNAMICS
ORBITS
PROTONS
SOLAR WIND
SPECTROMETERS
STOCHASTIC PROCESSES
SUN
TURBULENCE
ULTRAVIOLET RADIATION
BARYONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
FLUID MECHANICS
HADRONS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
MAIN SEQUENCE STARS
MATHEMATICS
MEASURING INSTRUMENTS
MECHANICS
NUCLEONS
RADIATIONS
SOLAR ACTIVITY
STARS
STELLAR ACTIVITY
STELLAR WINDS