Scientists at the Naval Research Laboratory have discovered a previously unreported solar feature – Coronal Cells – where high-temperature coronal emission is confined to discrete plumes that extend upward from unipolar concentrations of magnetic flux.
The NRL researchers think that future studies of these cellular regions will lead to an improved understanding of magnetic field line reconnection at the boundaries of coronal holes, and how these changes are transmitted outward into the solar wind. This research is published in the March 20 issue of the Astrophysical Journal.
NASA provided financial support through their Heliophysics Guest Investigator Program and their Living With a Star Program.
Drs. Neil Sheeley and Harry Warren, researchers in NRL’s Space Science Division, describe these Coronal Cells as appearing in discrete bundles “like candles on a birthday cake.” The researchers discovered the cells in ultraviolet emission lines formed at temperatures around one-million degrees Kelvin.
Although the researchers made their discovery using high-resolution images from the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory (SDO), they also observed the cells on ultraviolet images from STEREO-A and -B spacecraft recently, and from the Solar and Heliospheric Observatory (SOHO) in 2000 near the previous sunspot maximum. In addition, they used Doppler images, constructed from the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft, to deduce that the outflow is faster at the centers of the cells than at their boundaries.
The researchers used time-lapse sequences of Fe XII 193 Å coronal images to follow these special regions as they were carried across the solar disk by the 27-day solar rotation.