The Ages of Type I and Type II Subgiants
Open Access
- 1 April 1959
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 119 (2) , 124-133
- https://doi.org/10.1093/mnras/119.2.124
Abstract
Evolutionary sequences corresponding closely to the lower portions of (i) the globular cluster sequences, (ii) the M67 sequence, have been worked out with the aid of the IBM 704 computer. These lower portions of the sequences determine the ages of the Type I and Type II stars. By using observed magnitudes for certain nearby Type I stars of large trigonometrical parallax, together with the condition that Type II stars be older than Type I stars, it is concluded: (1) that the cluster-type variables cannot be brighter than M V = + 0.6, (2) that the age of the Galaxy must be greater than 10 10 years. Evidence is also given that the initial helium content of Type II stars was low.Keywords
This publication has 0 references indexed in Scilit: