Analysis of EUV limb brightening observations from ATM

✍ Scribed by George L. Withbroe; John T. Mariska

• Publisher: Springer
• Year: 1976
• Tongue: English
• Weight: 932 KB
• Volume: 48
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00153328

✦ Synopsis

A comparison of limb brightening measurements with theoretical limb brightening curves calculated for simple atmospheric models indicates that a significant fraction of the EUV emission from lines formed in the transition layer comes from spicules. We find that spicules contribute about 20% of the total quiet Sun intensity for lines of the C u, C m, N m, and O vI ions. The uncertainty in the magnitude of the percentage is about a factor of 2. The EUV-emission scale heights above the limb are consistent with the assumption that the variation with height of the number of EUV-emitting spicules is the same as for Ha-emitting spicules. Optical depths derived for the C u 3.1335 and C m A977 lines yield estimates for the pressure P = neT in the transition layer, log P = 14.7:50.5, that are in good agreement with pressures derived under the assumption that the transition layer is in pressure equilibrium with the chromosphere and corona.