Abstract
view Abstract Citations (17) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Emission Spectrum of the Hydrogen Balmer Series Observed above the Solar Limb from SKYLAB. II. Active Regions . . . . Feldman, U. ; Doschek, G. A. Abstract Electron densities are determined from the Stark broadening of Balmer hydrogen lines at 2" above the limb over three active regions. The spectra were recorded by the NRL slit spectrograph on Skylab. The density was found to be the same for all three regions and is 2 x 1011 with an error of less than 15% in fitting the theoretical curves to the data. The intensity falloff of the hydrogen lines above the limb over the active regions is compared with previous results obtained over a quiet Sun region and a polar coronal hole. The falloff is also compared with the intensity falloff of optically thin lines of Si II, Mg II, C II, singly ionized metals, and the neutral element, O I, recorded over a quiet Sun region. From this comparison, the temperature of the hydrogen plasma in all of the quiet and active regions that we observed is no more than about 8000 K. The intensity decrease of the hydrogen lines is the same as the intensity falloff of intersystem lines of 01. Nonthermal velocities of the hydrogen lines over the active regions are also derived. At 2" above the limb, these range from 0 km 1 to about 15 km s - . The lines of high members of the Balmer series are in Boltzmann equilibrium. The hydrogen observations are combined with our previous observations of singly ionized elements and are compared with observations of spicule s. Subject headings: Sun: chromosphere - Sun: corona - Sun: spectra Publication: The Astrophysical Journal Pub Date: March 1977 DOI: 10.1086/155115 Bibcode: 1977ApJ...212..913F full text sources ADS |
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