English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The solar orona is known to be a hot plasma phenomenon with the ele tron temperature T 1 10 6 K and low density n e 10 8 m 3 . It is observed in lines of high ionized elements in wide spe tral region. The strongest oronal lines in the visible spe trum are the lines of Fe X ( 6374 A), Fe XIV ( 5303 A), and Ca XV ( 6374 A) with T = (1 3) 10 6 K. However, sin e 1868, a faint H -emission in the orona, having T (10 4 10 5 ) K, has been observed more than on e during and out of the solar e lipses from the Earth. A review of the results of the old orona investigations is given in [1℄. Su essful observations of the old orona were also obtained in [2{ 4℄. Modern X-ray and EUV spa e observations also show that the orona is very dynami and inhomogeneous by its stru ture [5℄. The aim of this investigation was to sear h the old oronal emission during the solar e lipse on August 11, 1999 and to dete t its temperature. The observations were arried out in Bulgaria on the Bla k seashore. A horizontal solar instrument, onsisting of two oelostat mirrors, feeding two parallel tubes with identi al opti al and signal registration systems, was used to photograph the solar orona in three wavelengths. This installation, assembled in Sternberg Institute, was exploited for the rst time during the observations in August of 1999. The Fabry{Perot interferometers for the H , K CaII and Fe XIV lines together with the orresponding interferen e lters were employed, two of them were repla ed onsequently in one tube. The interferen e lters with the full widths of 15 A for the Fe XIV and H lines and 40 A for the K CaII line were used as the premono hromators. The observations, instrument and the method of the treatment are des ribed in more details in [6℄.

Search and investigation of cold emission in the solar corona of August 11, 1999