An interferometric study of the HH 288 molecular outflow^*

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
² Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France
³ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany

Corresponding author: F. Gueth, gueth@iram.fr

Received: 29 January 2001
Accepted: 18 June 2001

Abstract

We present an interferometric study of the CO line emission in the HH 288 molecular outflow. The IRAM Plateau de Bure interferometer was used to obtain an 11-field mosaic covering the whole flow (~2 pc) with an angular resolution of about (7000 AU at a distance of 2 kpc). The data were complemented with short-spacings derived from IRAM 30-m observations. The exciting source of HH 288, IRAS 00342+6347, is a young (dynamical age of the outflow a few 10⁴ years) intermediate-mass (bolometric luminosity , envelope mass 6 to ) embedded protostar. This source is likely to be an intermediate-mass counterpart of a classical Class 0 low-mass protostar. HH 288 is actually a quadrupolar outflow, and the angular resolution provided by the interferometric observations allows us to rule out models involving limb-brightened walls of a wide-angle single flow to explain such a morphology. The presence of two protostars in the central condensation is the most appealing explanation to account for the presence of the two flows. While the small East-West flow has a quite simple morphology and kinematics, the large North-South flow includes several overlapping structures, created by successive ejection events. Large collimated limb-brightened cavities are observed, with high-velocity material located along or near the flow axis. The internal structure of HH 288, including morphological coincidence between the CO and H₂ emission, supports prompt entrainment at the head of large bow-shocks as the main formation process of molecular outflows from intermediate-mass protostars.