Coronal structures deduced from photospheric magnetic field and He I λ10830 observations

The intensity of chromospheric structures observed in He I λ1083 nm is strongly modulated by overlying coronal radiation. For this reason, observations in He I λ1083 nm and their detailed comparison with photospheric magnetic fields and the X-ray corona allows us to deduce some aspects of coronal structures and of the topology of the coronal magnetic fields, particularly important at times when there are no direct coronal disk observations available. This paper discusses what He I λ1083 nm spectroheliograms can tell us about the short- and long-term evolution of the coronal magnetic fields, focusing on coronal holes, the large-scale, long-lived two ‘ribbon’ flare that follow the filament eruptions, and small-scale, short-lived dark points. The National Solar Observatory/Kitt Peak He I λ1083 nm and magnetic field data are compared with direct observations of the coronal structure from the Yohkoh Soft X-ray Telescope.