Mapping Excitation in the Inner Regions of the Planetary Nebula NGC 5189 Using HST WFC3 Imaging

Ashkbiz Danehkar, Margarita Karovska, W. Peter Maksym, Rodolfo Montez Jr.
Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA

Date: Received 2017 October 2; revised 2017 November 20; accepted 2017 November 28; published 2018 January 1

Abstract:

The planetary nebula (PN) NGC 5189 around a Wolf-Rayet [WO] central star demonstrates one of the most remarkable complex morphologies among PNe with many multi-scale structures, showing evidence of multiple outbursts from an AGB progenitor. In this study we use multi-wavelength Hubble Space Telescope Wide Field Camera 3 (WFC3) observations to study the morphology of the inner $0.3$pc $\times 0.2$pc region surrounding the central binary that appears to be a relic of a more recent outburst of the progenitor AGB star. We applied diagnostic diagrams based on emission line ratios of H$\alpha$$\lambda$6563, [OIII]$\lambda$5007, and [SII] $\lambda \lambda$6717,6731 images to identify the location and morphology of low-ionization structures within the inner nebula. We distinguished two inner, low-ionization envelopes from the ionized gas, within a radius of 55 arcsec ($\sim 0.15$ pc) extending from the central star: a large envelope expanding toward the northeast, and its smaller counterpart envelope in the opposite direction toward the southwest of the nebula. These low-ionization envelopes are surrounded by a highly-ionized gaseous environment. We believe that these low-ionization expanding envelopes are a result of a powerful outburst from the post-AGB star that created shocked wind regions as they propagate through the previously expelled material along a symmetric axis. Our diagnostic mapping using high-angular resolution line emission imaging can provide a novel approach to detection of low-ionization regions in other PNe, especially those showing a complex multi-scale morphology.
 
Keywords: planetary nebulae: individual (NGC 5189) -- ISM: jets and outflows
 
Journal Reference: A. Danehkar, M. Karovska, W. P. Maksym, and R. Montez Jr. The Astrophysical Journal, 852(2):87, 2018. doi:10.3847/1538-4357/aa9e8c