Membership of Low-Mass Stars in the Open Clusters Alpha Persei and IC 4665
Abstract
The results of a combined astrometric, photometric, and spectroscopic membership survey in two intermediate -age open clusters, alpha Persei and IC 4665, are presented. Emphasis has been placed on determining the low-mass membership of these clusters in an effort to determine if these clusters are significantly deficient in low-mass stars compared to the general field. In alpha Per, over 130 low-mass new members have been identified to M_{rm v} ~eq 12.5, almost doubling the previous number of known members. The new membership information suggests a slight upward revision of alpha Per's age to ~8 times 10^7 yrs. Allowing for survey incompleteness, one cannot reject the idea that the luminosity function is consistent with the field luminosity function to M_{rm v} ~eq 9 or 10. The study of IC 4665 has been more limited but has resulted in the identification of numerous new proper motion/photometry candidate members and of at least 12 M dwarfs that are likely members. While IC 4665 has been previously thought unlikely to possess any additional members beyond M_{rm v} ~eq 3.5, the present study shows that the cluster membership extends to at least M_{rm v} ~eq 10. From reasonable assumptions, it is shown that the idea that this cluster's luminosity function is consistent with the field luminosity function cannot be rejected at the present time. The new cluster members found in this study will be useful not only in the investigation of cluster properties such as age, luminosity function, and spatial distribution, but also in future studies of stellar evolution, angular momentum evolution, and lithium abundances. The present study has demonstrated the ability of combined astrometric, photometric, and spectroscopic methods to identify low -mass stars in clusters.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1991
- Bibcode:
- 1991PhDT........48P
- Keywords:
-
- ALPHA PERSEI;
- Physics: Astronomy and Astrophysics