A Disk Wind Driving the Rotating Molecular Outflow in CB 26

Abstract

We present the ^12 CO ( J = 2–1) sensitive molecular line and 1.3 mm continuum observations from the Submillimeter Array (SMA) of the bipolar outflow associated with the young star located in the Bok globule known as CB 26. The SMA observations were carried out in its extended configuration allowing us to study the kinematics and structure of the outflow with about 1″ or 140 au resolution. We find that the dusty and edge-on circumstellar disk related to the outflow has a projected spatial (deconvolved) size of 196 ± 31 × 42 ± 29 au with a total (gas+dust) mass of 0.031 ± 0.015 M _⊙ . We estimated a dynamical mass for the central object of 0.66 ± 0.03 M _⊙ , and the mass of the molecular outflow of 5 ± 1.5 × 10 ^−5 M _⊙ . All these values are consistent with recent estimations. The observations confirm that the outflow rotation has a similar orientation to that of the edge-on disk. For the outflow, we find that the following quantities: the rotation velocity (∼1–3 km s ^−1 ), specific angular momentum (∼200–700 au km s ^−1 ), and launching radius (∼15–35 au) decrease with the height above the midplane, as observed in other molecular rotating outflows. The radius (∼180–280 au) and expansion velocity (∼2–4 km s ^−1 ) also increase with the height above the disk midplane for z 0 au these quantities do not exhibit this behavior. Estimations of the outflow linear momentum rate, outflow angular momentum rate, and accretion luminosity seem to be well explained by the presence of a disk wind in CB 26.

Keywords

• Star formation
• Stellar winds