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Alfven waves in the solar corona.
S Tomczyk1, S W McIntosh, S L Keil
1High Altitude Observatory (HAO), National Center for Atmospheric Research (NCAR), Post Office Box 3000, Boulder, CO 80307-3000, USA. tomczyk@ucar.edu
Science (New York, N.Y.)
|September 1, 2007
Summary
Alfvén waves were detected in the Sun's corona, but the observed waves appear too weak to explain coronal heating. Unresolved waves might still hold the key to understanding solar coronal heating mechanisms.
Area of Science:
- Solar physics
- Plasma astrophysics
- Heliophysics
Background:
- The Sun's corona reaches millions of degrees, a phenomenon not fully explained by current models.
- Alfvén waves are proposed to transport energy from the photosphere to the corona, potentially driving this heating.
- Understanding coronal heating is crucial for predicting space weather and its impact on Earth.
Purpose of the Study:
- To detect and characterize Alfvén waves in the solar corona.
- To assess the energy transport capability of observed Alfvén waves for coronal heating.
- To investigate the role of Alfvén waves in the Sun's atmospheric energy balance.
Main Methods:
- Utilized the Coronal Multi-Channel Polarimeter (CoMP) instrument at the National Solar Observatory.
- Analyzed intensity, line-of-sight velocity, and linear polarization data of the solar corona.
- Focused on the FeXIII 1074.7-nanometer coronal emission line.
Main Results:
- Detected ubiquitous upward propagating Alfvén waves in the solar corona.
- Measured wave phase speeds ranging from 1 to 4 megameters per second.
- Inferred wave trajectories consistent with magnetic field direction from polarization measurements.
Conclusions:
- The spatially resolved Alfvén waves detected carry insufficient energy to heat the solar corona.
- The possibility remains that unresolved or smaller-scale Alfvén waves could provide the necessary energy for coronal heating.
- Further investigation into unresolved wave populations is needed to fully understand coronal energy transport.
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