Photographs of Stars, Star-Clusters and Nebulae Book contents
- Frontmatter
- PREFACE
- Contents
- LIST OF THE PLATES
- INSTRUMENTS
- LIST OF ABBREVIATIONS ADOPTED IN THIS WORK
- The Negatives–measurement of the photographic field–scales of the enlargements
- Epoch of the Fiducial Stars, A.D. 1900
- Table
- Deterioration of the Negatives
- Effects of Atmospheric Grlare and of Diffraction upon the films of photographic plates
- Arrangement of the Plates
- Method for micro-puncturing the photographic discs of stars on plates to obtain their optical centres for purposes of measurement
- Star Catalogues and Photographic Charts
- Duration of the effective exposures given to photographic plates in the 20-inch reflector
- Are the millions of Stars and the numerous Nebulosities, which are now known to exist, limited in number and extent; and do they consequently indicate that the Universe, of which the Solar System constitutes a part, is only one member of a greater Stellar Universe?
- The Evolution of Stellar Systems
- Inferences suggested by examination of the Photographs
- Description of the Photographs
- Description of the Photographs
Description of the Photographs
Published online by Cambridge University Press: 05 July 2011
- Frontmatter
- PREFACE
- Contents
- LIST OF THE PLATES
- INSTRUMENTS
- LIST OF ABBREVIATIONS ADOPTED IN THIS WORK
- The Negatives–measurement of the photographic field–scales of the enlargements
- Epoch of the Fiducial Stars, A.D. 1900
- Table
- Deterioration of the Negatives
- Effects of Atmospheric Grlare and of Diffraction upon the films of photographic plates
- Arrangement of the Plates
- Method for micro-puncturing the photographic discs of stars on plates to obtain their optical centres for purposes of measurement
- Star Catalogues and Photographic Charts
- Duration of the effective exposures given to photographic plates in the 20-inch reflector
- Are the millions of Stars and the numerous Nebulosities, which are now known to exist, limited in number and extent; and do they consequently indicate that the Universe, of which the Solar System constitutes a part, is only one member of a greater Stellar Universe?
- The Evolution of Stellar Systems
- Inferences suggested by examination of the Photographs
- Description of the Photographs
- Description of the Photographs
Summary
N.G.C. 7089. G.C. 4678. h 2125.
Sir J. Herschel, in the G.C., describes it as partly resolvable; a globular cluster; bright; very large; gradually, pretty much brighter in the middle; resolvable into stars; stars extremely faint. A drawing of it is given in the Phil. Trans., 1833, pl. XVI., fig. 88, and 1844, pl. XVIII., fig. 88.
Lord Kosse (Obs. of Neb. and Cl., p. 162) describes the cluster, and gives measurements of the position angles, and distances of some of the stars.
The photograph shows the cluster with a large central mass of nebulosity so dense as to obliterate the star-images; but the faint stars surrounding it are arranged in a manner suggestive of their origin from a spiral nebula.
The three clusters depicted on Plate XXVIII., and there are others of a similar character but not yet published, are strongly suggestive of, if they do not indisputably prove, that the same principle of aggregation has been in operation to cause the origin and development of each of these clusters, and I have not been able to detect any clearer evidence of their origin than that of development from spiral nebulæ.
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- Information
- Photographs of Stars, Star-Clusters and NebulaeTogether with Records of Results Obtained in the Pursuit of Celestial Photography, pp. 177 - 178Publisher: Cambridge University PressPrint publication year: 2010First published in: 1899