chromospheric network

chromospheric network

A large-scale cellular pattern in the solar chromosphere. It is most clearly defined at the center of the Sun's disk in the monochromatic light of the K Fraunhofer line of singly ionized calcium (Ca II), when it appears as a mosaic of cells outlined (at least partly) by bright mottles. Its appearance is similar though less pronounced in the core of the hydrogen-alpha (Hα) line of neutral hydrogen, but in the wings the mottles appear dark instead of bright. Both bright and dark mottles have been tentatively identified with spicules, which are visible beyond the Sun's limb. They seem to differ only in their height above the photosphere, bright mottles being situated in the lower chromosphere, dark mottles at heights of up to about 10 000 km.

The chromospheric network coincides with the underlying supergranulation, the horizontal flow within each supergranular cell concentrating magnetic flux at its boundary; at the boundary an enhanced vertical magnetic field is produced, which is responsible for the localized excess heating that manifests itself as the bright mottles.

chromospheric network

[¦krō·mə¦sfir·ik ′net‚wərk]
(astronomy)
A large-scale cellular pattern into which the motion of gas in the chromosphere is ordered by magnetic folds, and which is visible in spectroheliograms taken at the Hα (hydrogen alpha) line at a wavelength of about 656 nanometers and in other spectral regions.