Astrophys. J., 852, 5-5 (2018/January-1)
Linking signatures of accretion with magnetic field measurements-line profiles are not significantly different in magnetic and non-magnetic Herbig Ae/Be stars.
REITER M., CALVET N., THANATHIBODEE T., KRAUS S., CAULEY P.W., MONNIER J., RUBINSTEIN A., AARNIO A. and HARRIES T.J.
Abstract (from CDS):
Herbig Ae/Be stars are young, pre-main-sequence stars that sample the transition in structure and evolution between low- and high-mass stars, providing a key test of accretion processes in higher-mass stars. Few Herbig Ae/Be stars have detected magnetic fields, calling into question whether the magnetospheric accretion paradigm developed for low-mass stars can be scaled to higher masses. We present He I 10830 Å line profiles for 64 Herbig Ae/Be stars with a magnetic field measurement in order to test magnetospheric accretion in the physical regime where its efficacy remains uncertain. Of the five stars with a magnetic field detection, one shows redshifted absorption, indicative of infall, and two show blueshifted absorption, tracing mass outflow. The fraction of redshifted and blueshifted absorption profiles in the non-magnetic Herbig Ae/Be stars is remarkably similar, suggesting that the stellar magnetic field does not affect gas kinematics traced by He I 10830 Å. Line profile morphology does not correlate with the luminosity, rotation rate, mass accretion rate, or disk inclination. Only the detection of a magnetic field and a nearly face-on disk inclination show a correlation (albeit for a few sources). This provides further evidence for weaker dipoles and more complex field topologies as stars develop a radiative envelope. The small number of magnetic Herbig Ae/Be stars has already called into question whether magnetospheric accretion can be scaled to higher masses; accretion signatures are not substantially different in magnetic Herbig Ae/Be stars, casting further doubt that they accrete in the same manner as classical T Tauri stars.
© 2017. The American Astronomical Society. All rights reserved.
accretion, accretion disks - stars: magnetic field - stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be - stars: variables: T Tauri, Herbig Ae/Be
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