The origin, excitation, and evolution of subarcsecond outflows near T Tauri^*

¹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany e-mail: [gustafsson;herbst]@mpia.de
² Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: kristensen@strw.leidenuniv.nl
³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany e-mail: mkasper@eso.org
⁴ Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V9E 2E7, Canada

Received: 8 December 2009
Accepted: 7 April 2010

Abstract

Aims. We study the complex H₂ outflows in the inner 300 AU of the young triple star system T Tauri, with the goal of understanding the origin, excitation and evolution of the circumstellar matter.

Methods. Using high spatial resolution, integral-field spectroscopy in the J and K photometric bands from SINFONI/VLT, we trace the spatial distribution of 12 H₂ ro-vibrational emission lines, as well as one forbidden Fe II line. The ratio of line strengths provides a two-dimensional view of both the variable extinction and excitation temperature in this region, while the line-center velocities, coupled with previously published imagery, allow an assessment of the 3D space velocities and evolution of the outflows.

Results. Several spatially distinct flows – some with a bow shock structure – appear within 15 of the stars. Data taken two years apart clearly show the evolution of these flows. Some structures move and evolve, while others are stationary in the plane of the sky. The two-dimensional extinction map shows that the extinction between T Tau N and T Tau S is very high. In addition to being clumpy the extincting material forms part of a filament that extends to the east of the stars. In areas with strong line emission, the v = 1–0 S(1)/v = 2–1 S(1) line ratio ranges from 8 to 20, indicating that all of the observed H₂ is shock excited. The outflows in the immediate vicinity of T Tau S span ~270° and are all blue-shifted, suggesting that they are produced by more than one star. We propose that T Tau N drives the east-west outflow, while T Tau Sa and T Tau Sb are the sources of the southeast-northwest and a previously undetected southwest outflow, respectively. There is a large spatial overlap between the [Fe II] line emission and previously measured UV fluorescent H₂ emission, showing that both may be produced in J-shocks.