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A mesmerizing spectacle of solar activity, captured by the European Space Agency’s Solar Orbiter, reveals a twisting plasma streamer ejected from the sun following a coronal mass ejection (CME). This video footage of the solar event may offer crucial insights into the mechanisms behind magnetic energy release that power both the solar wind and substantial eruptions on the sun.
Helical Streamer Observation
The captivating helical streamer, observed by the Solar Orbiter on October 12, 2022, persisted for over three hours. During this time, it extended to an impressive 2 million kilometers (1.3 million miles), transporting solar plasma and magnetic energy away from the sun’s surface.
Utilizing its Metis instrument, the Solar Orbiter effectively employed a coronagraph to diminish the intense glare emanating from the main body of the sun. This ingenious technique enabled the spacecraft to discern the sun’s faint outer atmosphere, known as the corona, in both visible and ultraviolet light. Streamers within this wispy corona are typically visible from Earth during a total solar eclipse.
Solar Orbiter’s observation of the massive, 2 million kilometer-long helical streamer following a CME.
Insights into Solar Wind and CMEs
While helical structures in the solar corona have been previously documented, this recent event marks an unprecedented level of detail and duration of observation. The development of this streamer is now furnishing solar physicists with crucial insights into the driving forces behind the solar wind and coronal mass ejections (CMEs).
Researching the Streamer’s Origins
Researchers, spearheaded by Paolo Romano from the National Institute for Astrophysics at the Astrophysical Observatory of Catania in Italy, have meticulously examined the spiraling streamer. They successfully traced its trajectory back to its point of origin within the lower corona.
Magnetic Energy and Interchange Reconnection
Their findings suggest a model where magnetic energy accumulates in tightly stretched magnetic field lines at the corona’s base. The corona itself contains coronal holes, regions where magnetic field lines are open, extending into space rather than looping back to the sun’s surface (photosphere).
The solar wind emanates from these coronal holes. A process known as interchange reconnection occurs, involving magnetic reconnection – the breaking and reforming of magnetic field lines, releasing energy – between open and closed magnetic fields in the lower corona. Large-scale reconnection events can unleash sufficient energy to trigger solar flares and erupting magnetic filaments, culminating in CMEs.
On a smaller scale, interchange reconnection fuels continuous jets that inject energy into the corona and through coronal holes. These jets energize Alfvén waves, magnetic disturbances in solar plasma. These waves, in turn, propel plasma and matter through coronal holes, contributing to the solar wind.
Twisted Flux Rope Formation
The observed twisting streamer’s origin is explained by observations from Solar Orbiter and NASA’s Parker Solar Probe. These missions have led solar physicists to believe that escaping plasma from significant interchange reconnection events takes the form of a “twisted flux rope.”
A flux rope is essentially a tube of magnetic energy originating from a solar filament, which is a channel of plasma held by closed magnetic fields. Interchange reconnection between the filament and open magnetic field lines unleashes energy, powering a CME. This eruption manifests as a powerful jet surging through the solar corona and into space, carrying plasma and forming the CME. This flux tube constitutes the bright core of a CME.
The Solar Orbiter’s observation precisely captured this phenomenon: a twisting flux tube as the aftermath of a substantial interchange reconnection event that expelled a large CME into space.
Magnetic Switchbacks and Solar Mysteries
Computer simulations indicate that the twisted nature of the flux tube is a natural outcome of prolonged interchange reconnection. Solar Orbiter’s Metis instrument provided further details, revealing that the tilt of the twisting features in the escaping flux tube diminishes with height above the sun. This suggests that magnetic field lines become increasingly aligned radially as they propagate into the solar system.
Romano’s team proposes that these perturbations could generate magnetic switchbacks. These are sudden reversals in the magnetic field direction within the solar wind, observed by both Solar Orbiter and Parker Solar Probe, creating a zig-zagging pattern.
For decades, key solar enigmas, such as the corona’s extreme heating and the energy source for solar wind and CMEs, have remained unsolved. However, with Solar Orbiter and Parker Solar Probe venturing closer to the sun than ever before, these missions are finally unlocking the sun’s most profound secrets.