CoMStOC IV: Multiwaveband Observations of Sunspot and Plage-Associated Coronal Emission

Simultaneous observations of an active region located near central meridian were obtained with the Very Large Array, the Solar Maximum Mission X- ray Polychromator, and the Beijing Observatory magnetograph on 18 December 1987, during the Coronal Magnetic Structures Observing Campaign COMSTOC. An asymmetric loop-like structure connects the strong leading sunspot with a nearby region of opposite polarity. Both 6 and 20 cm emission lies along this structure, rather than over the sunspot, with higher frequency emission originating closer to the footpoint inside the sunspot. The 20 cm emission is due to a superposition of 2nd and 3rd harmonic gyroemission, where the field strength is 16- G- 300 G, while the 6 cm emission is due to the 3rd harmonic gyroemission from a region where the magnetic field strength ranges from 547 583 G. A high value of the Alfven speed of 40,000 kmsec, is obtained at the location of the 6 cm source, with somewhat lower values of 10,000 - 20,000 km sec, at the location of the 20 cm emission. At the location of the 6 cm source, the plasma temperature diminishes with height from 2.5 x 1000000 K at 5000 km to 1.3 x 1000000 K at 15, 000km.