Coronal Bright Points

Abstract

Soft X-ray images of the inner corona obtained with the AS&E spectrograph telescope aboard Skylab revealed the presence of coronal bright points in far greater numbers than had previously been suspected. Bright points are associated with bipolar magnetic features with typical diameters of 1–2 × 104 km, mean lifetime of eight hours and magnetic flux 1019–1020 Mx. Several thousand bright points emerge over the solar surface per day, thereby bringing up more magnetic flux than is contributed by the larger active regions during the period of observation, May 1973 to February 1974. Bright points identified in X-ray photographs are seen as small (5–10″) emission features in ground-based Hα and Ca K spectroheliograms as well as in transition region lines observed in other Skylab instruments. Typical bright point temperatures are 1.5–2 × 106 K and typical densities are ∼ 5 × 109 cm−3.