An Envelope Disrupted by a Quadrupolar Outflow in the Pre-Planetary Nebula IRAS19475+3119

TL;DR

This study reveals how a quadrupolar pre-planetary nebula's envelope is disrupted by bipolar outflows, using high-resolution CO observations to analyze its structure and kinematics.

Contribution

It provides the first detailed CO J=2-1 observational analysis of the quadrupolar PPN IRAS19475+3119, highlighting envelope disruption by bipolar outflows.

Findings

Detection of high-velocity E-W bipolar outflow.

Identification of a slowly expanding torus-like envelope.

Evidence of envelope disruption by bipolar outflows.

Abstract

IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar lobes, one in the east-west (E-W) direction and one in the southeast-northwest (SE-NW) direction. We have observed it in CO J=2-1 with the Submillimeter Array at ~ 1" resolution. The E-W bipolar lobe is known to trace a bipolar outflow and it is detected at high velocity. The SE-NW bipolar lobe appears at low velocity, and could trace a bipolar outflow moving in the plane of the sky. Two compact clumps are seen at low velocity around the common waist of the two bipolar lobes, spatially coincident with the two emission peaks in the NIR, tracing dense envelope material. They are found to trace the two limb-brightened edges of a slowly expanding torus-like circumstellar envelope produced in the late AGB phase. This torus-like envelope originally could be either a torus or a spherical shell, and it appears as it is now because of the two pairs of cavities along the two bipolar lobes. Thus, the envelope appears to be disrupted by the two bipolar outflows in the PPN phase.