"Distance mapping" and the 3-D structure of BB +30 3639

TL;DR

This paper constructs a detailed 3-D model of planetary nebula BD +30 3639 using morpho-kinematic techniques, introduces a new 'distance mapping' method for better distance estimation, and reveals nebula-environment interactions.

Contribution

It introduces the 'distance mapping' technique for improved 3-D modeling and distance measurement of planetary nebulae, applied to BD +30 3639.

Findings

Determined the nebula's distance as 1.52 ± 0.21 kpc.

Revealed decreasing velocity field with distance from the star.

Identified interaction with ambient H2 gas.

Abstract

BD +30 3639 is a member of a group of uncommon planetary nebula with Wolf-Rayet central star and higher expansion velocities in [O III] than in [N II] lines. Images and high-resolution spectra from the literature are used in order to construct a 3-D model of the nebula using the morpho-kinematic code SHAPE. We find that two homologous expansion laws are needed for the [N II] and [O III] shell. We conclude that the internal velocity field of BD +30 3639 decreases with the distance from the central star at least between the [O III] and [N II] shells. A cylindrical velocity component is used to replicate the high-speed bipolar collimated outflows. We also present a new kinematic analysis technique called "distance mapping". It uses the observed proper motion vectors and the 3-D velocity field to generate maps that can be used as a constraint to the morpho-kinematic modeling with SHAPE as well as improve the accuracy for distance determination. It is applied to BD+30 3639 using 178 internal proper motion vectors from Li et al. (2002) and our 3-D velocity field to determine a distance of 1.52 \pm 0.21 kpc. Finally, we find evidence for an interaction between the eastern part of nebula and the ambient H2 molecular gas.