A study of the globular cluster M3

• Main Author: Sandage, Allan
• Format: Others
• Published: 1953
• Online Access: https://thesis.library.caltech.edu/4199/1/Sandage_ar_1953.pdf; Sandage, Allan (1953) A study of the globular cluster M3. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/06G7-RG84. https://resolver.caltech.edu/CaltechETD:etd-10212002-160549 <https://resolver.caltech.edu/CaltechETD:etd-10212002-160549>

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The color-magnitude diagram for the globular cluster M3 has been obtained to absolute magnitude M[subscript v] = +6. The main sequence has been found, extending from M[subscript v] = +3.5 to the limit of the data. The photometric parallax of m - M = 15.63 is found by fitting the apparent magnitude diagram to O. J. Eggen's and H. L. Johnson's diagram for stars in the solar neighborhood. The absolute magnitude of the cluster type variables in M3 is calibrated by this method. The value M[subscript v]= 0.0 for these stars is correct within [...]. This value is of significance for a decision on a new distance scale for the extragalactic nebulae in the observable universe. The luminosity function is obtained to M[subscript v] = 6.8 for M3. From M[subscript Bol]= +2 to +4 a linear relation between log [...] (M) and M[subsript Bol] exists. The results of Chapter 3 show that this relation is expected if the sequences of the color-magnitude diagram are evolutionary in origin. Application of a theory of evolution to the color magnitude diagram gives an age of 5 x 10[superscript 9] years since the formation of the main sequence in M3 and M92. Further consequences of an evolutionary interpretation of the data are discussed in Chapter 3 and it is concluded that all evidence now available lends support to the evolutionary explanation of the sequences in the color-magnitude diagram.