The findings, detailed in the *Proceedings of the National Academy of Sciences (PNAS)*, offer insights into solar magnetism and the Sun's polar regions. "No one can say for certain what is happening at the solar poles," said Mausumi Dikpati, NSF NCAR senior scientist and study lead. "But this new research gives us an intriguing look at what we might expect to find when we are able, for the first time, to observe the solar poles."
The study was supported by NSF and NASA, with computing resources provided by NSF NCAR's Cheyenne and Derecho systems.
A Puzzle at the Solar Poles
Polar vortices, seen on various planets, form in fluids surrounding rotating bodies due to the Coriolis force. On Earth, these vortices confine cold air to the poles, weakening occasionally and shifting frigid air toward the midlatitudes. NASA's Juno and Cassini missions have revealed similar phenomena on Jupiter and Saturn, providing critical atmospheric insights.
Scientists have observed polar vortices on Mars, Venus, Uranus, Neptune, and Titan, Saturn's moon. Thus, it is conceivable that the Sun, surrounded by plasma influenced by magnetism, may also host such structures. The Sun's magnetism complicates understanding vortex formation, as direct observations of the poles remain uncharted.
Modeling Solar Vortices
With no direct observations available, the research team turned to computer simulations. The models suggested that the Sun develops polar vortices in a unique manner aligned with its magnetic cycle. A ring of vortices forms at approximately 55 degrees latitude, resembling Earth's Arctic Circle, coinciding with a magnetic event known as the "rush to the poles."
This movement results in the magnetic field at the solar poles flipping polarity at each solar cycle's peak, leaving behind vortices that move poleward before vanishing at solar maximum. The quantity and configuration of these vortices vary based on the cycle's intensity.
These simulations contribute to a deeper understanding of solar magnetism and could clarify how magnetic field strength at the poles relates to predicting solar cycle strength. The outcomes may also inform the timing of future solar missions.
Implications for Future Space Missions
Simulations suggest that polar vortices should be visible during most of the solar cycle, except at solar maximum. Co-author Scott McIntosh of Lynker emphasized the importance of mission timing: "You could launch a solar mission, and it could arrive to observe the poles at completely the wrong time." The Solar Orbiter, a collaborative NASA and European Space Agency mission, is set to provide initial observations, though it will approach during solar maximum.
McIntosh highlighted the need for missions designed to capture multiple viewpoints of the Sun: "Our conceptual boundary now is that we are operating with only one viewpoint. To make significant progress, we must have the observations we need to test our hypotheses and confirm whether simulations like these are correct."
Research Report:*A Magnetohydrodynamic Mechanism for the Formation of Solar Polar Vortices*
Related Links
University Corporation for Atmospheric Research
Solar Science News at SpaceDaily
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