Radiometric Observation of the Solar Corona During the Eclipse of 1941, September 21 / მზის კორონის რადიომეტრული დაკვირვება 1941 წლის 21 სექტემბრის მზის სრული დაბნელების დროს

Nikonov, V.B. and ნიკონოვი, ვ. (1943) Radiometric Observation of the Solar Corona During the Eclipse of 1941, September 21 / მზის კორონის რადიომეტრული დაკვირვება 1941 წლის 21 სექტემბრის მზის სრული დაბნელების დროს. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (7). pp. 33-72.


Download (48MB) | Preview


The attempt of radiometric determination of the total radiation of the solar Corona during the eclipse of 1936, June 19 yielded some indirect indications on the possible presence of an infra-red excess in the coronal radiation. G. A. Tikhov, who has brought an analogous conclusion with respect to the scattered Corona, tries to explain the observed decrease of the colour temperature of the Corona by the thermal radiation due to particles of cosmic matter. Meanwhile the current opinion is that the coronal radiation is of purely electronic nature. It is well known that in this case the energy distribution in the coronal spectrum must be identical with that in the solar one and no infra-red excess can exist. Photo-electric colorimetry of the 1937 eclipse by J. Stebbins and A. Whitford is in favour of this hypothesis. Thus, the question on the amount and even on the very existence of thermal radiation, and consequently on the presence of dust particles in the solar Corona, remains open. This circumstance induced us to make during the eclipse of 1941, September 21 an attempt of direct attack on the question as to the presence of an infra-red excess in the coronal radiation. We choose for this purpose the way of radiometric comparison of the spectral composition of the total radiation of the Corona and the Sun, deriving their water cell absorptions. The observational data underlying the value ot the infra-red excess, as derived by us, are insufficient. Possibly, this value is somewhat exaggerated. But we think that the existence of a certain excess is real and is in favour of the supposition of the presence of thermal radiation in the Solar Corona. The emission lines in the Corona may exert some influence on the value of the infra-red excess. An accurate account of this effect is now impossible, as the emission lines lying in the region of absorption of the water cell are still unknown. Nevertheless one can suppose on the basis of the estimates by Ludendorff, relating to emission lines of short wavelenght, that the effect of all emission lines is insignificant and can be neglected, at least in the first approximation. In connection with the question on the reality of the infrared excess it Is worthy to note that, as shown by V. Th. Hase in case of purely electronic character of the Corona, the effect of obliteration of the absorption lines must lead not to coincidence but to dissimilarity of the observed energy distribution in the spectra of Corona and Sun. Therefore the papers by Ludendorff and Grotrian hitherto regarded as principal confirmation of the hypothesis of electronic nature of the Corona, must rather be considered as being in certain contradiction with this hypothesis. In virtue of all these considerations we find necessary to repeat the present work during future eclipses in order to prove experimentally the existence of thermal radiation in the Corona and the reality of variations of its total radiation. The latter seems to us quite possible as the variations of the coronal radiation can plausibly be explained by the increase of brightness and area of the coronal rays, connected, as well known, with the eruptive activity of the Sun. When repeating the present work one must introduce a number of improvements, the most imoprtant of which are: 1) The photographic record of the galvanometer deflections. The higher accuracy and objectivity of this method would allow to use a less sensitive galvanometer of shorter period, say Zernicke Zb and thus to double the number of readings. It is also desirable to replace the thermocouple used by a more sensitive one of the same type. 2)Standardization must be done at the eclipse day, before and after observations of totality. 3)One must secure a spectroscopic determination of the content of water vapour in the atmosphere for the eclipse day. A still greater increase to the speed and accuracy of the observation may be achieved by the construction of a new model of a coronal radiometer, optical scheme of which, is a combination of both—outlined in the preface to our paper on the radiometry of the 1936 eclipse. This radiometer could be used for an attempt of observation of the outer circular zone of the Corona, where the effect of emission lines does not exist. December, 1942

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 25 May 2018 10:10
Last Modified: 25 May 2018 10:10

Actions (login required)

View Item View Item