3D spatio-kinematic modeling of Abell 48, a planetary nebula around a Wolf-Rayet [WN] star

TL;DR

This study presents a detailed 3D spatio-kinematic model of the planetary nebula Abell 48, revealing its deformed elliptical shell, expansion velocities, and surrounding structures, linked to its rare Wolf-Rayet [WN] star nucleus.

Contribution

It provides the first comprehensive 3D kinematic analysis of Abell 48 using integral field data and the SHAPE modeling tool, uncovering its complex morphology and kinematic features.

Findings

Elliptical toroidal shell with 23 arcsec radius and 15 arcsec thickness.

Hα expansion velocity of approximately 35 km/s.

Presence of low-ionization structures likely formed by shock interactions.

Abstract

The planetary nebula (PN) Abell 48 (PN G029.0+00.4) is around a rare Wolf-Rayet [WN5] star whose stellar history is as yet unknown. Using the integral field observations of the H$\alpha$ $\lambda$6563 and [N II] $\lambda$6584 line emissions, we conducted a comprehensive spatio-kinematic analysis of this PN. A three-dimensional spatio-kinematic ionization model was developed with the kinematic modeling tool SHAPE to replicate the observed spatially-resolved velocity channels and position--velocity diagrams. According to our kinematic analysis of the H$\alpha$ emission, this object possesses a deformed elliptic toroidal shell with an outer radius of 23 arcsec and a thickness of 15 arcsec associated with an integrated H$\alpha$ emission-line expansion of $\sim 35 \pm 5$ km s$^{-1}$, a maximum poloidal expansion of around $70 \pm 20$ km s$^{-1}$ at an inclination angle of $\sim 30^{\circ}$ with respect to the line of sight, and a position angle of $\sim 130^{\circ}$ measured from east toward north in the equatorial coordinate system. Furthermore, [N II] kinematic modeling reveals the presence of narrow ($\sim 3$ arcsec) exterior low-ionization structures surrounding the main elliptical shell, which could have formed as a result of shock collisions with the interstellar medium. The torus-shaped morphology of this PN could be related to its unusual hydrogen-deficient [WN] nucleus that needs to be inspected further.