Исследование поляризационных свойств образований лунной поверхности но элекрофотометрическим измерениям / An investigation of polarizing properties of the lunar surface formations based on the electrophotometric measurements / მთვარის ზედაპირის წარმონაქმნთა პოლარიზაციული თვისებების გამოკვლევა ელექტროფოტომეტრული გაზომვების მიხედვით

Djapiashvili, V.P. and ჯაფიაშვილი, ვ. and Джапиашвили, В.П. (1957) Исследование поляризационных свойств образований лунной поверхности но элекрофотометрическим измерениям / An investigation of polarizing properties of the lunar surface formations based on the electrophotometric measurements / მთვარის ზედაპირის წარმონაქმნთა პოლარიზაციული თვისებების გამოკვლევა ელექტროფოტომეტრული გაზომვების მიხედვით. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (21). pp. 8-165.

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Abstract

The resulls of the eleclropolarimetry made at the Abastumani astrophysical observatory in 1950—1953 are presented. The 33-cm reflector (Nasmith focus 1:15) and the stellar electrophotometer [146, 147] with a herapathite polaroid were used. A special investigation showed that the systematic error due to the reflection from the mirrors of the telescope reaches 4% in polarization. For various phase angles of the Moon the mirrors influence differently the degree and the plane of polarization of the lunar light. Near the quadrature moments the rate of polarization is always increased because of this error. On the contrary, its decreasing is observed in some cases near the full moon moments. This probably means the so called negative polarization effect first mentioned by B. Lyot [131]. The formulae (12.4) and (12.3) by V. G. Fessenkov [135] were used for the determination of the degree and the plane of polarization of the lunar light. When measuring the intensity of the light a 0.3 mm (12."3) diaphragm was used. This corresponds in the average to the area about 23 km in diameter. The mean values of the mean quadratic error for the degree and the angle of the polarization are ±0.005 and ±l°.7, respectively. The total number of the measurements of the 41 objects of the lunar surface, made during 148 nights, is 1371. About 164 curves, representing the dependence of the polarization on the phase, the angle of incidence, reflection and asimuth, were drawn. The conclusions based on the analysis of these curves are as follows. The dependence of the polarization rate on the moon's phase [120, 124, 131] is confirmed. About all of the studied objects show the maximum light polarization near the quadratic moments. The details showing a slight displacement of the maximum of polarization relatively to the quadrature moment towards the increase of the phase are situated in the eastern part of the Moon's disk. Those showing the displacement towards the decrease of the phase are in the western part. Posidonius being the only exception. Consequently, the noticed phenomenon has a symmetrical character relatively to the full moon moment. The objects without any displacement of their maximum polarization moments are mainly concentrated along the zero meridian (+25°--10° of stenographic longitude). The objects bearing different morphological and physical properties polarize the light with different capacities. The light reflected from the Moon's seas is mostly polarized; that from the lands and mountains—least of all. The crater bottoms and the bright rays have an intermediate position from this point of view, polarization capasities of the latter being slightly higher than that of the craters. Thus, for instance, the mean maximum for the seas and the bays equals 18.3% for the craters — 13.2%, lands and bright rays—13.9%. This involves tho conclusion that the lunar seas must be of later origin than the other formations. At the time near the full moon the light reflected from all the observed objects, independently of their position and morphological and physical properties, reveals the minimum polarization, its value being in the average about 3.6%. The shapes of the curves representing for the different objects the dependence of tho polarization on the phase angles and the angles of incidence are very peculiar extremely sharp minimum at the full moon for some of them (Archimedes, Copernicus etc.) and very wide one for others (Cyrillus. Ptolemaeus etc.). The polarization rate increases mainly with the asimuth. But the more detailed examination of the corresponding curves reveals some variety for different areas. These noted peculiarities of separate lunar formations are probably due to their individual physical characteristics. Tho examined correlation between the maximum polarization values and tho sizes of the craters appears to bo rather low, although a slight decrease of tho former with tho increase of the diameter is to be noted. This last fact is in agreement with the so called morphological law „less-yonger-lower", established by Levy and Piuseaux and indicating the endogenic (vulcanogenic) origin of the lunar relief. April, 1955

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 28 May 2018 09:49
Last Modified: 28 May 2018 09:49
URI: http://eprints.iliauni.edu.ge/id/eprint/8011

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