The Stars of High Luminosity - Pasta blanda

THE STARS OF HIGH LUMINOSITY HARVARD OBSERVATORY MONOGRAPHS No. 3 THE STARS OF HIGH LUMINOSITY BY CECILIA H. PAYNE Published for the Observatory by the McGRAW-HILL QOK COMPANY, INC. NEW YORK AITO LONDON 1930 PREFACE THE physical study of stars by means of their spectra has gone far in the last five years. In 1925 I attempted, in Stellar Atmospheres Harvard Monograph No. i, to survey and analyze the current knowledge of the subject. lonization theory was then less than five years old, and its application was as yet general and empirical. Since 1925 there have been considerable advances in technique, theory has been extended, and, above all, there has been an accumulation of relevant observations. Since Stellar Atmospheres is out of print, and to some extent also out of date, I have been encouraged to replace it by the present volume. The Stars of High Luminosity is in no sense a revision of the earlier book the changing face of the subject, and the growth of my own outlook, have dictated the form of the present treatment. Moreover it is difficult to enumerate exactly the parts of the former monograph that are superseded in the present one. The whole picture is fuller, the detail more convincing, than they were five years ago. I believe that the chief advance besides the improved technique that replaces qualitative by roughly quantitative results resides in the wider correlation of data, and its effect on the background of astro physical thought matters entering the text implicitly rather than explicitly. In many ways the results are less clear-cut than they were five years ago, a consequence of the greater wealth of data the picture of the stellar atmosphere sketched in Monograph No. imay well seem simpler and more con vincing than the present one. Although the analysis of the stellar atmosphere is still in its early phases, the present treatment marks a definite stage. It carries the work as far as I believe it can be carried with the vi PREFACE kind of material available to me spectra of comparatively short dispersion, either unstandardized or standardized by simple and unrefined methods. It seems as though further work demands greater refinement of method, and probably also far larger dispersion, if the scope of the study is to be enlarged, or much greater accuracy attained. But qualitative data have their uses. In the short history of ionization theory the majority of important advances have been made on the basis of simple, even qualitative observations. We do not yet know enough to interpret the more refined data, and assiduous sifting and classifying of facts will greatly help us to rough out our theories, and to decide which refined data are most worth pursuing. Especially is this thought stressed in regard to variable stars, which seem to be almost untouched from the broader astrophysical aspects included for reasons of completeness, they have usurped a disproportionately large fraction of the book. But I am not even sure that it would be indefensible to make them the starting point of the whole attack on the star of high luminosity. I should like to express my indebtedness to those who have helped me with material and the exchange of thought Professor H. H. Plaskett, Professor B. P. Gerasimovi, and, above all, Dr. Shapley for his stimulating and generous discussion of most of the subjects of this monograph. Professor Rosseland, Dr. ten Bruggencate, Mr. Bok, and Miss Williams have each read part of the manuscript, and I am grateful for their helpful criticisms. C. H. P. CAMBRIDGE, MASS. October, 1930. CONTENTS PAGS PREFACE v LIST OF TABLES xi I. INTRODUCTORY CHAPTER I. SYNOPSIS OF THE PROBLEM 3 1. Synopsis of Later Chapters 3 2. The Significance of High Luminosity 6 3. Applications of the High Luminosity Star 9 4. The Leading Problems 9 5. The Spectroscopic Approach 10 II. ON THE PHOTOMETRY OF SPECTRA. . . 12 6. Development of Spectrophotometry 12 7. The Photometric Problem .... 14 8. The Standard Source 18 9...