The kinematics of the nebular shells around low mass progenitors of PNe with low metallicity

TL;DR

This study investigates the internal kinematics of 26 low-metallicity planetary nebulae from low-mass progenitors, revealing generally low expansion velocities likely driven by weak stellar winds, thus enhancing understanding of nebular evolution.

Contribution

It provides the largest sample to date of low-metallicity PNe kinematics, characterizing their expansion velocities and linking these to central star properties.

Findings

Most PNe have expansion velocities less than 20 km/s.

Low velocities are likely due to weak stellar winds.

Results support the connection between nebular kinematics and central star characteristics.

Abstract

We analyze the internal kinematics of 26 Planetary Nebulae (PNe) with low metallicity that appear to derive from progenitor stars of the lowest masses, including the halo PN population. Based upon spatially-resolved, long-slit, echelle spectroscopy drawn from the San Pedro M\'artir Kinematic Catalogue of PNe (L\'opez et al. 2012), we characterize the kinematics of these PNe measuring their global expansion velocities based upon the largest sample used to date for this purpose. We find kinematics that follow the trends observed and predicted in other studies, but also find that most of the PNe studied here tend to have expansion velocities less than 20 km/s in all of the emission lines considered. The low expansion velocities that we observe in this sample of low metallicity planetary nebulae with low mass progenitors are most likely a consequence of a weak central star wind driving the kinematics of the nebular shell. This study complements previous results (Pereyra et al. 2013, and references therein) that link the expansion velocities of the PN shells with the characteristics of the central star.