The Magnetic Fields of Classical T Tauri Stars

Abstract

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.

25 pages, 5 figures

References in corpus (4)

• Magnetic field generation in fully convective rotating spheres
• T Tauri stellar magnetic fields: He I measurements
• Spectropolarimetry of the Classical T Tauri Star TW Hydrae
• CaII Infrared triplet line models in Classical T Tauri stars

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• A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau
• Magnetocentrifugally Driven Flows from Young Stars and Disks. VI. Accretion with a Multipole Stellar Field
• Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry of T Tauri Stars
• X-ray emission from dense plasma in CTTSs: Hydrodynamic modeling of the accretion shock
• The non-dipolar magnetic fields of accreting T Tauri stars
• Magnetic Properties of Young Stars in the TW Hydrae Association
• First Magnetic Field Detection on a Class I Protostar
• The effect of a stellar magnetic variation on the jet velocity
• Magnetic field observations of low-mass stars