Star cluster parameters without isochrones

Conference item

An algorithm for objective Least Squares solution of star cluster HR diagrams (HRDs) is outlined, stimulated by the limited usefulness of 1-dimensional isochrones. The underlying model includes distributions of multiple stars and of quantities such as metallicity and interstellar extinction that vary from star to star. The synthesized quantity compared with observations is Areal density (A) of HRD points. Computational speed and precision are indispensible for overall success and are gained by use of a stellar evolution program based on approximation functions. Differentiability of A is greatly enhanced by two sub-algorithms, designated as pixel sharing and re-scaling. Distributions are handled by a new statistical method called Functional Statistics that was developed for HRDs but applies as well to many other problems traditionally treated by Monte Carlo methods. Applications of this method to synthetic and real clusters were mainly successful. Schemes to promote flexibility and several presently deferred problems are discussed.

Authors: Wilson, R

• Publication status: Published
• Journal: EVOLUTION OF BINARY AND MULTIPLE STAR SYSTEMS
• Volume: 229
• Pages: 49-58
• Publication date: 2001-01-01
• Event title: Conference on Evolution of Binary and Multiple Star Systems
• ISBN: 1583810617
• Keywords: GLOBULAR-CLUSTERS; LUMINOSITY FUNCTIONS