The solar wind, a continuous stream of charged particles emanating from our parent star, spreads spherically throughout the Solar System and envelops the planets. On Earth it causes the northern and southern auroras and sometimes triggers geomagnetic storms that threaten satellites.
New observations from Europe’s Solar Orbiter spacecraft now offer an answer to the mechanism that generates the solar wind, one of the greatest mysteries in astrophysics.
Researchers who analyzed the data reported in the journal Science (“Picoflare jets power the solar wind emerging from a coronal hole on the Sun“) that they detected small jets emanating from the corona, the Sun’s atmosphere, and blasting charged particles into space at supersonic speeds. These are short-lived structures with a length of a few hundred kilometers, which disappear within 20 to 100 seconds.
These jets were dubbed by the researchers “picoflare jets” because of their small size (“pico-” is the subdivision prefix that stands for a trillionth of a unit). The picoflares were spotted inside “corona holes,” regions of the solar surface that appear dark due to their relatively low temperature. In these regions, gaps in the Sun’s magnetic field allow charged particles to escape more easily.
The researchers estimate that the jets are a “significant source” of the solar wind, although other mechanisms are also possible. More data could come from new observations by the Solar Orbiter and the corresponding US Parker Solar Probe mission.
