On the absorption in the windows of zone of avoidance / კოსმოსური შთანთქმის შესახებ "აცილების ზონის სარკმლებში"

Melnikov, O.A. and Мельников, О. and მელნიკოვი, ო. (1945) On the absorption in the windows of zone of avoidance / კოსმოსური შთანთქმის შესახებ "აცილების ზონის სარკმლებში". აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (8). pp. 51-56.

[img]
Preview
Text
1945-8–3.pdf

Download (2MB) | Preview

Abstract

The relation between the color-excess of the stars and the number of extragalactic nebulae for the whole Galaxy has been studied by Seares. It would be rather interesting to investigate the color-excesses of H stars in the windows of the zone of avoidance. As we know, the large window is situated south of galactic equator, between the longitudes i$o° and 180°. In this region of the zone of avoidance faint extragalactic nebulae are found (Hubble). Successive approximations give us f according to p and E. The color-excesses for a given distance must be reduced E0 relating to one kiloparsec. Otherwise the low value of Ex in the window may be explained by the fact that the observed stars are close to the Sun. As we sec from the table the,mean color-excess per kiloparsec in the window is less than in the neighbouring regions. The account of that factor of the decrease of the density of the absorbing matter with the removal from the galactic plane according to the Berman formulas does not change the result as these four regions have low galactic latitudes. The mean observed color-excess is represented as a circle on the given scale (Fig. 1). Shapley's investigating the number of extragalactic nebulae to the definite stellar magnitude in the window near the galactic centre found are much less absorption. In fact, the number of extragalactic nebulae observed in this window us greater than that in the window near the anticentre. Shapley considers the window near the centre so much transparent that we can see the faint variable stars at the distance more than 10 kiloparsecs i. e- probably beyond the galactic centre. The connection of the small color-excesses with the presence of extragalactic nebulae within zone of avoidance shows that the general coefficient due to large particles (meteors) and other nonselective factors according to the law is small. The author himself studying the absorption on the base of Cepheid, came to the same order of the value for photographic absorption: The presence of the large window does not change markedly the mean absorption coefficient. This conclusion is fairly clear as the whole zone of avoidance consists of separate little windows and dark nebulae i. e. it has, as we know a rather spotted nature. Less than 10 well-known dark nebulae can already give as significant absorption and determining apq we always have in view only the mean value in longitude, latitude and distance. This idea was suggested in the works of Ambarzumian and Gordeladse, Greenstein and others. Conclusions: i) The comparative study of color-excess of B stars in the galactic window and neighbouring regions indicates the insignificant role of nonselective factors in the mean absorption. 2) The absorption coefficient [according to 84 B stars equals 1m.2 i. e. is close to the value obtained from other sources. December, 1942.

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 16 Jul 2018 10:45
Last Modified: 16 Jul 2018 10:45
URI: http://eprints.iliauni.edu.ge/id/eprint/8241

Actions (login required)

View Item View Item