What can we learn about the kinematics of bright extragalactic planetary nebulae

TL;DR

This study investigates the kinematic information obtainable from high-resolution spectroscopy of bright extragalactic planetary nebulae, demonstrating that [O III] line widths reliably reflect nebular shell kinematics despite observational limitations.

Contribution

It shows that [O III] line widths in extragalactic planetary nebulae are consistent with Hα and are robust against S/N variations, aiding kinematic studies of distant nebulae.

Findings

[O III] and Hα line widths are similar.

Line width measurement is S/N independent.

Deviations from Gaussian shape are minimal.

Abstract

We present high resolution spectroscopy in the [\ion{O}{3}]$\lambda$5007 and H$\alpha$ lines of bright planetary nebulae in the Milky Way bulge and the dwarf galaxies M32, Fornax, Sagittarius, and NGC 6822 obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir using the Manchester Echelle Spectrograph. We use the high signal-to-noise (S/N) observations of Milky Way bulge planetary nebulae to explore what kinematic information can be determined reliably when observing extragalactic planetary nebulae in the [\ion{O}{3}]$\lambda$5007 line at modest S/N. We find that the intrinsic line widths measured in [\ion{O}{3}]$\lambda$5007 and H$\alpha$ are very similar. Over the range of S/N available in this sample, the line width we measure is independent of the S/N. Finally, deviations from a Gaussian line shape are small. Thus, the line width of the [\ion{O}{3}]$\lambda$5007 line in bright extragalactic planetary nebulae should reflect the kinematics of most of the mass in the ionized nebular shell.