| Extensive research has been done on the evolution of young low mass T Tauri stars (TTS), and a paradigm has been developed that successfully explains how the star grows by the accretion of matter from a circumstellar disk. It is currently a matter of debate whether or not the same paradigm can be applied to the higher mass counterpart Herbig Ae stars. In this dissertation, I propose to address this issue. By investigating a wide range of phenomena using ground-based and satellite observing platforms, I will construct detailed observational pictures of the two prototypical Herbig Ae stars, HD163296 and AB Aur. Then, I will test whether or not this model can explain all the phenomena associated with these two stars.;First, my research characterized the bipolar collimated outflow from HD163296. Using narrowband coronagraphic imagery with the Goddard Fabry-Perot, I discovered a chain of six previously unreported Herbig-Haro (HH) knots along the redshifted counterjet spanning greater than 27 arcseconds, and three HH knots along the blueshifted jet. Combining Hubble Space Telescope imagery and spectroscopy, I found a striking asymmetry in velocity, momentum and ionization between the two lobes of the outflow. Such asymmetries have been found in TTS, and can readily be explained through the same paradigm of magnetospheric accretion successfully applied to TTS.;Next, by piecing together a wide range of data for AB Aur, I found evidence for magnetospheric accretion with the detection of excess continuum emission and semi-forbidden line emission in the ultraviolet. Reviewing archival spectra from the International Ultraviolet Explorer for AB Aur and five other Herbig Ae stars known to be powering microjets, I found a correlation between the Magnesium II wind absorption profile and inclination, which correlation strongly suggests that AB Aur is also powering a microjet, although currently, high resolution imagers have failed to detect jet signatures. |
