Poster Abstracts

Name/Affiliation:  Paul Wilson Cauley (Rice University)

Title:  Herbig Ae/Be vs T Tauri Stars: Accretion and Outflows with 1-micron Spectroscopy

Abstract:
Herbig Ae/Be stars (HAEBES) are often described as the higher mass counterparts to T Tauri stars (TTSs). Although some HAEBES display similar accretion and outflow signatures as classical TTSs (CTTSs), the overall line profile statistics indicate significant differences in the mass flow frequencies for the two groups. In this talk we present the first high-resolution study of the He I 10830 line in a large sample of HAEBES. He I 10830 is an excellent tracer of outflows and accretion near the star-disk interaction region due to the meta-stability of the lower energy level and has been used extensively to investigate the mass flows around CTTSs. We interpret our line profiles within the context of wind and accretion models developed for CTTSs and show that the frequency of occurrence for each type of line profile differs significantly between HAEBES and CTTSs, indicating that, in general, different star-disk interactions are at play in each mass regime. Our results also add to the growing evidence that HBe stars interact with their environments differently than HAe stars. We conclude that the accretion and outflow scenarios common to CTTSs cannot be applied blindly to HAEBES. In particular, the magnetospheric accretion, which can account for many of the observed properties of CTTSs, does not appear to be the dominant accretion mechanism in HAEBES.