| Title: | Interstellar absorption in the direction of the Crab nebula |
| Authors: | Brodskaya E.S. |
| Abstract: |
Interstellar absorption in the direction of the Crab nebulae has been determined from the color excesses of 86 O - F8 stars. Objective prism plates (dispersion 200 and 300 Å/mm at Hg) are used for the classification of the spectra. The color indices are found by the photographic method. The magnitude scales are based on available photoelectric observations. The measured magnitudes (mv) and color indices (C) are reduced to the B, V system according to the relations obtained by the author in [8]: B - V = C - 0,267C + 0,06. Visual absorption is computed from the relation AV = 3 EB-V. The absolute magnitudes of the stars are on the MK system, with the exception of A0 stars for which MV = +0m,5 is adopted [9]. The relation between AV and the distances is shown in fig. 2. At the distance of the Crab nebula of about 1100 pc, adopted at -present, AV = + 0m,70. The gas to dust density ratio is estimated, Pgas / Pdust = 120, using radio observations at 21 cm of the absorption spectra of the Crab nebula [10]. |
| Keywords: | Stars; Photometry; Spectral types |
| Publication: | Izvestiya Krymskoj Astrofizicheskoj Observatorii (IzKry). - 1963. - V. 30. - P.126. |
| Comments: | Tab. 1. Ref. 11. Fig. 2. Id.Map 1. |
| References: |
[8] E.S. Brodskaya. IzKry, 24, 160, 1960. [9] K. Osawa. Astrophys. J., 130, 59, 1959. [10] B.G. Clark, V. Radhakrishnan, R.W. Wilson. Astrophys. J., 135, 151, 1962. |
| Bib.Code: | 1963IzKry..30..126B |
| Full-text: | PDF (442 kB); GIF (330 kB) |
1. W. Baade. Astrophys. J., 96, 188, 1942. 2. П.В. Щеглов. Астрон. ж., 34, вып.4, 671, 1957. 3. W.A. Hiltner. Astrophys. J. Suppl. ser., N 2, 389, 1956. 4. L. Woltjer. Bull. Astron. Netherl., 14, N 483, 1958. 5. В.И. Мороз. Астрон. ж., 37, вып.2, 265, 1960. 6. P. Pesch. Astrophys. J., 134, 602, 1961. 7. O'Dell (в печати). 8. E.S. Brodskaya. IzKry, 24, 160, 1960. 9. K. Osawa. Astrophys. J., 130, 59, 1959. 10. B.G. Clark, V. Radhakrishnan, R.W. Wilson. Astrophys. J., 135, 151, 1962. 11. H. Van de Hulst. Utrecht. Res., 11, 21, 2, 1949.
