Related Experiment Video
Updated: Jul 9, 2026
06:14
Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface
Published on: July 30, 2020
Chromospheric alfvenic waves strong enough to power the solar wind
B De Pontieu1, S W McIntosh, M Carlsson
1Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Organization ADBS, Building 252, Palo Alto, CA 94304, USA. bdp@lmsal.com
Science (New York, N.Y.)
|December 8, 2007
Summary
Strong Alfvén waves were detected in the Sun's chromosphere, providing a potential explanation for solar wind acceleration and coronal heating. These observations bridge a critical gap in understanding solar atmospheric dynamics.
Area of Science:
- Solar Physics
- Plasma Physics
- Astrophysics
Background:
- Alfvén waves are theorized to heat the Sun's corona and accelerate the solar wind.
- Direct observation of sufficiently strong Alfvén waves in the solar atmosphere has been lacking.
Purpose of the Study:
- To investigate the presence and characteristics of Alfvén waves in the solar atmosphere.
- To determine if observed Alfvén waves possess sufficient energy for coronal heating and solar wind acceleration.
Main Methods:
- Utilized high temporal and spatial resolution images from the Solar Optical Telescope on the Hinode satellite.
- Analyzed wave properties within the chromosphere, the layer between the solar surface and corona.
Main Results:
- Detected Alfvén waves with significant amplitudes (10-25 km/s) and periods (100-500 s) permeating the chromosphere.
- Estimated the energy flux carried by these waves.
Conclusions:
- The observed Alfvén waves are energetic enough to potentially accelerate the solar wind.
- These waves may also contribute to heating the quiet solar corona.
Related Concept Videos
01:20Momentum And Radiation Pressure
An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because electromagnetic waves contain and transport momentum. The force accounts for the wave's radiation pressure exerted on the object. Maxwell's prediction was confirmed in 1903 by Nichols and Hull by precisely measuring radiation pressures with a torsion balance. The measuring instrument had mirrors suspended from a fiber kept inside a glass container. Nichols...
01:22Energy Carried By Electromagnetic Waves
Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun's warmth. At other times, it is subtle, such as the unfelt energy of gamma rays, which can destroy living cells. Electromagnetic waves bring energy into a system through their electric and magnetic fields. These fields can exert forces and move charges in the system and, thus, do work on them. However, there is energy in an electromagnetic wave,...
02:45Nuclear Fusion
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
01:09Radiation Pressure: Problem Solving
The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave's momentum also gets transferred to the surface when an electromagnetic wave is entirely absorbed by it. The rate at which momentum is transmitted to an absorbing surface perpendicular to the propagation direction equals the force on the surface.
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
01:23Faraday Disk Dynamo
A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular velocity in the magnetic field, perpendicular to the disk's plane. The rotation of the disk causes a change in magnetic flux, which induces an emf, causing opposite charges to develop on the rim and in the center of the disk. The polarity of the induced emf can be determined by the direction of the magnetic field and the direction of the...
01:30Electromagnetic Waves in Matter
Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, or glass.
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...