We present observations and results of radiance and irradiance studies completed by SoHO-SUMER during the past solar cycle. We find that the cycle variation in Ly-alpha irradiance as observed by e.g. UARS-SOLSTICE can not be explained by quiet sun radiance data, and conclude that the explanation must be related to differences in the Ly-alpha radiance of various solar features and changes in their fractional distribution over the solar cycle. Consequently, we studied the emission of the hydrogen Ly-alpha line in various solar features - for the first time observed by SUMER on disk in full resolution - to investigate the imprint of the magnetic field on line profile and radiance distribution. We also compare quasi-simultaneous Ly-alpha and Ly-beta line profiles. Such high-resolution observations - not hampered by geocoronal absorption - have never been completed before.
@article{arxiv.1002.3551,
title = {Hydrogen Lyman emission through the solar cycle},
author = {W. Curdt and H. Tian},
journal= {arXiv preprint arXiv:1002.3551},
year = {2010}
}
Comments
6 pages, 4 figures, to appear in "Understanding a peculiar Solar Minimum", eds. S Cranmer, T.Hoeksema, J. Kohl, ASPC 2010