New tests of magnetospheric accretion in T Tauri stars.
JOHNS-KRULL C.M. and GAFFORD A.D.
Abstract (from CDS):
We examine three analytic theories of magnetospheric accretion onto classical T Tauri stars (CTTSs) under the assumption that the magnetic field strength does not vary appreciably from star to star. From these investigations we derive predicted relationships among the stellar mass, radius, rotation period, and disk accretion rate. Data from five studies of the accretion parameters of CTTSs are used to test the predicted correlations. We generally find that the data do not display the predicted correlations except for that predicted by the model of Shu et al. as detailed by Ostriker & Shu and extended here to include nondipole field topologies. Their identification of the trapped flux as an important quantity in the model appears to be critical for reconciling the observed data to the theory. While the data do generally support the extended Ostriker & Shu predictions, only one of the two studies for which the requisite data exist shows the highest correlation when considering all the relevant parameters. This suggests that great care must be taken when trying to use existing observations to test the theory.