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

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.