Witnessing the Shaping of the Archetypical “Butterfly” Planetary Nebula NGC 6302 with HST’s Wide Field Camera 3

We present initial analysis of a set of near-UV-to-near-IR Hubble Space Telescope Wide Field Camera 3 (WFC3) emission-line images of the planetary nebula (PN) NGC 6302, one of the brightest and more extreme examples of a pinched-waist, bipolar PN. This comprehensive suite of WFC3 images, obtained in over a dozen narrow- and broad-band filters in Fall 2019 and Spring 2020 (HST Cycle 27), is one of two “first-of-their-kind” panchromatic HST/WFC3 imaging surveys of PNe (the other targeted the well-studied PN NGC 7027; see Moraga et al., this meeting). Both surveys are designed to advance our understanding of the planetary nebula formation process and, in particular, to test models of binary-star-driven PN shaping. Our WFC3 survey of NGC 6302 has put an exclamation point on its long record of HST imaging, in the form of the discovery of extensive, “S-shaped” 1.64 micron [Fe II] emission. This emission reveals the present zones of energetic shocks generated by nebula-sculpting wind collisions. The [Fe II]-delineated shock fronts are restricted to the southern and northern limbs of the east and west lobes of the nebula, respectively, indicating the present directions — and surprisingly vast (~0.3 pc) reach — of ongoing fast, collimated outflows from the PN’s central engine. Comparison of the new WFC3 images with archival HST/WFC3 images from 2009 demonstrates the detailed expansion patterns within the nebula, and provides estimates of the dynamical ages of specific lobe structures. This comparison also indicates that the star located near the geometric center of the nebula, which was previously assigned “central star” status, is in fact not physically associated with NGC 6302 but is, instead, a foreground field star. The identification and nature of the source of NGC 6302’s energetic outflows evidently remains elusive, awaiting direct detection by JWST or ALMA.