Fluctuation in the number of extragalactic nebular and the galactic absorption / Флуктуации в числе внегалактических туманностей и галактическое поглощение

Ambarzumian, V.A. and ამბარცუმიანი, ვ. and Амбарцумиан, В.А. (1940) Fluctuation in the number of extragalactic nebular and the galactic absorption / Флуктуации в числе внегалактических туманностей и галактическое поглощение. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (4). pp. 17-26.

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Abstract

The earlier investigations of the cosmic absorption problem have shown that in our galaxy the absorbing layer has a rather complicated and irregular structure. In a statistical research of diffuse nebulae the author in collaboration with Sh- Gordeladse has shown that there is no genetic relation between diffuse nebulae and illuminating stars and the conclusion was suggested that a multitude of "unilluminated" nebulae is irregularly distributed in the space causing space absorption. It was also shown that these unilluminated nebulae absorb approximately one magnitude per kiloparsec and the absorption by each nebula was estimated as reaching 0.3 ph. mg. Greenstein came independently to the conclusion that the general cosmic absorption results from the combined absorption effect of a multitude of absorbing clouds: But he estimated the mean value of the optical thickness of each cloud as being 0.11. K r e i k e n has given Im as the value of the optical thickness of each cloud. Becker, when investigating the selective absorption in some directions, has found it necessary to attribute it to separate clouds situated at different distances from us. He derived the value of color-excess for the cosmic cloud and has found it to be 0.4 or 0.3. But derived the difference according to the observational data we can determine the values. The values for different galactic latitudes are listed in the table II. The mean value is which corresponds to the value obtained earlier. But it is necessary to note that this value characterizes only the average optical thicjness of unilluminated nebulae; separate nebulae may have quite different values for the optical thickness.

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 11 Jul 2018 11:21
Last Modified: 11 Jul 2018 11:21
URI: http://eprints.iliauni.edu.ge/id/eprint/8193

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