Panchromatic HST/WFC3 Imaging Studies of Young, Rapidly Evolving Planetary Nebulae. I. NGC 6302

TL;DR

This study uses HST/WFC3 imaging to reveal detailed structures and shock regions in the young, dust-rich planetary nebula NGC 6302, providing new insights into its morphology and central star location.

Contribution

It offers the first detailed near-UV to near-IR imaging of NGC 6302, identifying shock regions, dust structures, and clarifying the central star's position, advancing understanding of bipolar planetary nebulae.

Findings

Bright [Fe II] emission indicates shock zones from collimated winds.

Dusty toroidal structure bisects the nebula's polar lobes.

The previously identified central star is a foreground star.

Abstract

We present the results of a comprehensive, near-UV-to-near-IR Hubble Space Telescope WFC3 imaging study of the young planetary nebula (PN) NGC 6302, the archetype of the class of extreme bi-lobed, pinched-waist PNe that are rich in dust and molecular gas. The new WFC3 emission-line image suite clearly defines the dusty toroidal equatorial structure that bisects NGC 6302's polar lobes, and the fine structures (clumps, knots, and filaments) within the lobes. The most striking aspect of the new WFC3 image suite is the bright, S-shaped 1.64 micron [Fe II] emission that traces the southern interior of the east lobe rim and the northern interior of the west lobe rim, in point-symmetric fashion. We interpret this [Fe II] emitting region as a zone of shocks caused by ongoing, fast (~100 km/s), collimated, off-axis winds from NGC 6302's central star(s). The [Fe II] emission and a zone of dusty, N- and S-rich clumps near the nebular symmetry axis form wedge-shaped structures on opposite sides of the core, with boundaries marked by sharp azimuthal ionization gradients. Comparison of our new images with earlier HST/WFC3 imaging reveals that the object previously identified as NGC 6302's central star is a foreground field star. Shell-like inner lobe features may instead pinpoint the obscured central star's actual position within the nebula's dusty central torus. The juxtaposition of structures revealed in this HST/WFC3 imaging study of NGC 6302 presents a daunting challenge for models of the origin and evolution of bipolar PNe.