The ALMA early science view of FUor/EXor objects - IV. Misaligned outflows in the complex star-forming environment of V1647 Ori and McNeil's Nebula

Abstract

We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the star-forming environment surrounding V1647 Ori, an outbursting FUor/EXor pre-MS star. Dust continuum and the (J = 2 − 1) 12CO, 13CO, C18O molecular emission lines were observed to characterize the V1647 Ori circumstellar disc and any large scale molecular features present. We detect continuum emission from the circumstellar disc and determine a radius r = 40 au, inclination i = 17◦+6 −9 and total disc mass of Mdisc of ∼0.1 M . We do not identify any disc structures associated with nearby companions, massive planets or fragmentation. The molecular cloud environment surrounding V1647 Ori is both structured and complex. We confirm the presence of an excavated cavity north of V1647 Ori and have identified dense material at the base of the optical reflection nebula (McNeil’s Nebula) that is actively shaping its surrounding environment. Two distinct outflows have been detected with dynamical ages of ∼11,700 and 17,200 years. These outflows are misaligned suggesting disc precession over ∼5500 years as a result of anisotropic accretion events is responsible. The collimated outflows exhibit velocities of ∼2 km s−1 , similar in velocity to that of other FUor objects presented in this series but significantly slower than previous observations and model predictions. The V1647 Ori system is seemingly connected by an ”arm” of material to a large unresolved structure located ∼2000 to the west. The complex environment surrounding V1647 Ori suggests it is in the early stages of star formation which may relate to its classification as both an FUor and EXor type object.