An Extreme High-Velocity Bipolar Outflow in the Pre-Planetary Nebula IRAS 08005-2356

TL;DR

This study presents interferometric and single-dish observations of the pre-planetary nebula IRAS 08005-2356, revealing an extremely high-velocity bipolar outflow exceeding 200 km/s, likely launched from an accretion disk around a companion star.

Contribution

First detailed interferometric mapping of IRAS 08005-2356's high-velocity outflow, suggesting its origin from an accretion disk and providing indirect evidence through spectral analysis.

Findings

Detected outflow velocity ~200 km/s.

Outflow mass >0.1 solar masses.

Evidence for an accretion disk origin.

Abstract

We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 with an angular-resolution of ~1"-5", using the Submillimeter Array (SMA), in the 12CO J=2-1, 3-2, 13CO J=2-1 and SiO J=5-4 (v=0) lines. Single-dish observations, using the SMT 10-m, were made in these lines as well as in the CO J=4-3 and SiO J-6-5 (v=0) lines. The lines profiles are very broad, showing the presence of a massive (>0.1 Msun), extreme high-velocity outflow (V~200 km/s) directed along the nebular symmetry axis derived from the HST imaging of this object. The outflow's scalar momentum far exceeds that available from radiation pressure of the central post-AGB star, and it may be launched from an accretion disk around a main-sequence companion. We provide indirect evidence for such a disk from its previously published, broad H-alpha emission profile, which we propose results from Ly-beta emission generated in the disk followed by Raman-scattering in the innermost regions of a fast, neutral wind.