Plateau de Bure interferometer observations of the disk and outflow of HH 30

Abstract

Context. HH 30 is a well-known Pre-Main-Sequence star in Taurus. HST observations have revealed a flared, edge-on disk driving a highly-collimated optical jet, making this object a case study for the disk-jet-outflow paradigm. Aims. We searched for a molecular outflow, and attempted to better constrain the star and disk parameters. Methods. We obtained high angular resolution (∼1″) observations of the dust continuum at 2.7 and 1.3 mm, and of the 12CO 7 = 2-1, 13CO J = 2-1 and J= 1-0, C18O J= 1 -0 emissions around HH 30. A standard disk model is used to fit the 13CO J = 2-1 uv-plane visibilities and derive the disk properties, and the stellar mass. An ad hoc outflow model is used to reproduce the main properties of the 12CO J = 2-1 emission. Results. The rotation vector of the disk points toward the North-Eastern jet. The disk rotation is Keplerian: using a distance of 140 pc, we deduce a mass of 0.45 M ⊙ for the central star. The disk outer radius is 420 AU. A highly asymmetric outflow originates from the inner parts of the disk. Only its North-Eastern lobe was detected: it presents to first order a conical morphology with a 30° half opening angle and a constant (12 km s-1) radial velocity field. Outflow rotation was searched for but not found. The upper limit of the outflow rotation velocity is 1 km s-1 at 200 AU of the jet axis. Conclusions. HH 30 is a low mass TTauri of spectral type around M1 and age 1 to 4 Myr, surrounded by a medium size Keplerian disk, of mass around 4 × 10-3 M⊙. It beautifully illustrates the jet-disk-outflow interaction, being so far the only star to display a jet and outflow connected to a well defined Keplerian disk, but reveals a surprisingly asymmetric (one-sided) outflow despite a relatively symmetric jet. Furthermore, these observations do not enable to assign the origin of the molecular outflow to entrainment by the optical jet or to a disk wind. In the latter hypothesis, the lack of rotation would imply an origin in the inner 15 AU of the disk. © ESO 2006.