Dr. Herbig will carry out a two-part investigation with the Keck I telescope on Mauna Kea and its HIRES high-resolution spectrograph to (1) examine objects located above the T Tauri region in young clusters, where it is believed that massive (>= 3 solar mass) pre-main sequence stars in transit to B- and A-types on the zero-age main sequence should be found and (2) investigate two species of pre-main sequence stars (FUors and EXors) that, although very different spectroscopically and photometrically, are both subject to unpredictable brightenings from minimum light. Whether all intermediate-mass stars are subject to this instability is uncertain. This investigation will shed light on whether the planets on our solar system were once exposed to such actvity when the Sun was young.
