The space absorption of light in the nebula of the Pleades / Пространстенное поглощение света в туманности пеяд

Kharadze, E.K. and ხარაძე, ე.კ. and Харадзе, Е.К. (1940) The space absorption of light in the nebula of the Pleades / Пространстенное поглощение света в туманности пеяд. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (4). pp. 53-68.


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This article contains the results of an investigation of the space absorption of light in the nebula of the Pleiades by the well known method of Wolf. The photographic plate has been taken with one of 8" cameras of our observatory with two hour exposure. On this plate the bright, illuminated part of nebula is visible as covering an area I1/2X1. We have studied not only this area but the adjacent regions, as well. Fig. 1 represents the investigated surface of the sky. The area is divided into 30 equal parts having their designations from No 1 to No 30. Each of these parts is 0.35 square degree. The whole area Is 3X4°. The dotted line shows the boundaries of the visible part of the nebula. The Pleiades sequence studied by Henrietta S. Leavitt has been taken as a scale of the magnitudes. Table I lists the comparison stars. The star counts in three "normal" areas and one "theoretical" curve served for drawing the "normal" curve for comparisons in Wolf's diagrams. The results of the star counts in all 30 areas of investigated surface are given in Table III, which contains N (m) as well as log N(m) tabulated against the areas and the magnitudes m. All the 30 areas can be divided into three groups. The first of them contains areas No No 4, 9, 10, 11, 15, 16, 17, 22, 23, 26, 27 and 28. The curve given in Fig. 2, referring to the area No 4 can serve as a typical one for the whole group. The dotted lines of the Fig. Fig. 2, 3, 4 denote the curves |log N(m),m] related to the obscured areas the continuous line representing the normal curve. The second group contains the areas No No r, 2, 3, 5, 7, 12, 13, 14, 19, 20, 21 and 29 and the corresponding typical diagram is represented by Fig. 3. The areas No No 6, 8, 18, 24, 25 and 30 form the third group characterized by the diagram in Fig. 4. Fig. 5 represents the investigated region divided into different groups: the continuous line encompasses the areas of the first group, the broken line— the areas of the second group and the dotted one those of the third group. The arrows show the direction parallel to the galactic equator. The physical members of the Pleiades cluster are situated in front of the absorbing cloud and the break of the curve shows not only the beginning of the absorption but also the effect of the cluster. In the case of the areas of the second group the stars are imbedded in clouds of absorbing matter at very moderate distances, but at the distance of stars of 14m.5 it seems to set the effect of the main layer of absorbing matter. As regards the areas of the third group the absorbing cloud seems to be very tar affecting only the faintest stars. The diagram of Fig. 6 relates to the area covered with the illuminated part of the nebula only. Fig. 7 refers to the area situated toward SW from the centre of the Pleiades and it shows that the abssorbing cloud extends rather far. It will always be difficult to come to more or less definite conclusions concerning the character of the absorption in the Pleiades cluster if we use only Wolfs method. This difficulty will arise from the uncertainty of defining- the real boundaries of the cluster; it is not always easy to know the real cause of the bending of the curve in Wolfs diagram. But the quantitative investigation of the reflected light by the nebula, which must be the second part of the study of the problem of the space absorption in the Pleiades, can bring more certainty and clearness into the question, being at the same time a check for the results obtained by using Wolfs method. September, 1959.

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 11:22
Last Modified: 11 Jul 2018 11:22

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