A group of astronomers attempting to determine what heats and accelerates solar wind discovered that data from an ageing NASA spacecraft might provide some clues.
Justin Kasper of the Harvard-Smithsonian Center for Astrophysics and his team of astronomers processed an old NASA spacecraft’s entire 19-year record of solar wind temperatures, magnetic field, and energy readings and determined that the source of the heating in solar wind is ion cyclotron waves.
The sun emanates ion cyclotron waves and they course through the solar wind. They then heat the gas to millions of degrees and accelerate the flow to millions of miles per hour. Kasper and his team’s findings demonstrate that these ion cyclotron waves do exist and are quite active.
Chemical elements of the solar wind such as hydrogen, helium, and heavier ions, blow at different speeds; they have different temperatures; and, strangest of all, the temperatures change with direction.
The next step is to find out if ion cyclotron waves work the same way deep inside the sun’s atmosphere where the solar wind has its genesis. NASA will send a spacecraft into the sun itself to find the answer to this question.
In 2018, Solar Probe Plus will travel so deeply into the sun’s atmosphere that the sun will appear 23 times wider than it does from Earth. If designed properly, Solar Probe Plus will withstand temperatures greater than 1400 degrees Celsius and withstand radiation at levels never before experienced by a spacecraft. The mission’s goal is to sample the sun’s plasma and magnetic field at the very source of the solar wind.
Justin Kasper and his team described their findings and in February 28 edition of the Physical Review Letters: “Sensitive Test for Ion-Cyclotron Resonant Heating in the Solar Wind.”
