Ionized helium in prominences and in the chromosphere

✍ Scribed by Tadashi Hirayama

• Publisher: Springer
• Year: 1972
• Tongue: English
• Weight: 695 KB
• Volume: 24
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00153371

✦ Synopsis

It is found that HelI 4686 ,is emitted in ithe same cold region of < 10000 K as hydrogen, metal and neutral helium emission lines. This conclusion is based on the finding that the observed width of 24686 is the same as the calculated width of 24686. The calculated width is derived from the observed widths of hydrogen and metallic lines. The large intensity of Hen 4686 in < 10000 K can be explained by the ionization of Hell due to the UV radiation below 228 that comes from the corona and the transition region.

Loop Prominences: The very broad width (30 to 50 km s -1) of ~.4686 for two post-flare loop prominences shows that the Hell line is emitted in hot regions different from regions of hydrogen and metal emission. From the widths of the Balmer lines and many metallic lines the kinetic temperature for one loop is found to be 16000 K in one part and 7600 K in another part. The electron densities are 1012.~ cm -z and less than 1011-~ cm -~ respectively.

Chromosphere: The intensity of 24686 in the chromosphere can be interpreted in terms of a temperature of < 10000 K with the ionization due to UV radiation. But, since observations of the width of 24686 are not available, a definitive conclusion for the chromosphere cannot be reached.