University of California, Berkeley
The origin of stellar masses (and the initial mass function) and the origin of stellar angular momenta (and the distribution with mass of initial angular momenta) represent two fundamental, unsolved problems in stellar astronomy. Progress toward their solution requires developing a census of stellar populations in young clusters characterized by a range of initial conditions and environments. To derive stellar properties (masses, ages, rotational velocities), both photometric and spectroscopic observations of large samples of stars are needed. This necessitates the synthesis of information collected from a variety of telescopes with apertures in the 1m-4m range. I will illustrate the importance of access to such a complement of facilities by discussing the results of a recent investigation of the stellar population in the Orion Nebula Cluster (ONC). This study makes use of optical photometry, infrared photometry, and both high- and low- resolution optical spectroscopy for stars spanning a dynamic range in apparent magnitude of ~20 mag. The ONC has formed stars of all masses from < 0.1-50M and is < 1 Myr in age; the ability to derive individual stellar masses, ages, and rotational velocities, for a statistically significant sample of stars, allows direct measurement of initial mass, age, and rotational velocity distributions. In turn, the statistics provided by the ONC database allow us to use this region to inform our similarly motivated studies of stellar populations in young clusters spanning wide ranges in size, stellar density, environmental conditions, and eventually age. Small telescopes are critical to enabling these types of fundamental investigations.
A more detailed outline of this talk is available.