Dr. Kevin Covey
Harvard Smithsonian Center for Astrophysics

University of Florida Astronomy Colloquium - Nov. 1st, 2006

Surveying the Formation of Low-Mass Stars

The development of physically robust stellar evolution models represent one of the primary achievements of 20th century astronomy. Observations of millions of stars in diverse environments have motivated the development of these models, while also providing stringent empirical tests for their success.

Unfortunately, the physical processes that govern the earliest stages of a star's life are much more poorly understood; we lack robust, physically motivated descriptions of mass accretion and angular momentum by young stars. This shortcoming is partially due to the innate complexity of the star formation process, but it also reflects the difficulty involved in observing young stars during their main accretion phase.

Photometric and spectroscopic surveys of stars, both young and old, now provide opportunities to give precise, statistically robust empirical guidance to models of mass accretion and angular momentum evolution in young, low-mass stars. I will begin by describing the analysis of matched photometric surveys to measure the luminosity and mass functions of low-mass stars in the Galactic field with unprecedented precision. I will then present results from a spectroscopic survey of more than 50 embedded young stars in nearby star formation regions. Measurements of photospheric temperatures, rotation velocities, and emission line strengths from these spectra have provided clues to the evolutionary status of these objects, as well as to the physics of mass accretion and angular momentum evolution at young ages.