Extended (15 x 6AU) H_alpha emission around T Tau N

P. J. V. Garcia1,2, E. Thiébaut1

1 CRAL/Observatoire de Lyon, CNRS UMR 5574, France
2 CAUP, Portugal


We present an image of T Tauri N reconstructed from speckle interferometry observations made at the 3.6 m Canada-France-Hawaii telescope (CFHT). Two spectral windows, at H_alpha [6540-6580 A] and red continuum [6580-6840 A] were used.

The star is unresolved in the continuum (theta <= 0''038), setting an upper limit for its size of <= 5.3 AU (assuming a 140 pc distance). At H_alpha (continuum subtracted) two components are observed, an unresolved one with 70% of the H_alpha flux and a resolved 0''106 x 0''043 (15 x 6 AU) with 30%. The extended component is elongated in the North-South direction.

The current paradigm for T Tauri stars understands them as acretion-ejection systems consisting of a magnetospheric boundary layer (MBL), a stellar/disk jet and a disk corona. The extended H_alpha component scale, it's non-detection in the continuum, and T Tau H_alpha profile shape suggest that the extension is a disk corona.

H_alpha line profiles are currently interpreted as arising in the MBL. Our present observations show that, the corona emission contributes significantly (~ 1/3) to the H_alpha profile.


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