Investigating solar corona structures has led Paul Bellan, Caltech professor of applied physics, and his former graduate student Yang Zhang (Ph.D. '24) to discover a new equilibrium state of the magnetic field and its associated plasma. The solar corona, the outermost part of the sun's atmosphere, is much less dense than the sun's surface but is a million times hotter. The corona is composed of strong magnetic fields confining plasma, a gaseous soup of charged particles (electrons and ions).

The new equilibrium, called a double helix, applies not only to the solar corona but also to much larger astrophysical configurations such as the Double Helix Nebula located near the center of the Milky Way galaxy.

The study is published in the journal Physical Review Letters.

Solar corona structures such as flares often have the form of magnetic flux ropes: twisted tubes of plasma-containing magnetic fields. Such a rope can be visualized as a plasma-filled garden hose with a stripe wrapped around it in a helical pattern. An electric current flows along the length of the hose, and the helical stripe corresponds to the twisted magnetic field. Because it is charged, plasma conducts electric currents and is attached, or "frozen," into magnetic fields.

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