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Abstract We present Submillimeter Array (SMA) mapping of¹²COJ= 2 → 1,¹³COJ= 2 → 1, and CNN= 2 → 1 emission from the ring-like planetary nebula NGC 3132, one of the subjects of JWST Early Release Observation near-infrared imaging. The ∼5″ resolution SMA data demonstrate that the Southern Ring’s main, bright, molecule-rich ring is indeed an expanding ring, as opposed to a limb-brightened shell, in terms of its intrinsic (physical) structure. This suggests that NGC 3132 is a bipolar nebula viewed more or less pole-on (inclination ∼15°–30°). The SMA data furthermore reveal that the nebula harbors a second expanding molecular ring that is aligned almost orthogonally to the main, bright molecular ring. We propose that this two-ring structure is the remnant of an ellipsoidal molecular envelope of ejecta that terminated the progenitor star’s asymptotic giant branch evolution and was subsequently disrupted by a series of misaligned fast, collimated outflows or jets resulting from interactions between the progenitor and one or more companions. 

Abstract We present the results of a comprehensive, near-UV-to-near-IR Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) imaging study of the young planetary nebula (PN) NGC 6302, the archetype of the class of extreme bilobed, 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 μ m [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 −1 ), 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. 

Abstract The young and well-studied planetary nebula (PN) NGC 7027 harbors significant molecular gas that is irradiated by luminous, pointlike UV (central star) and diffuse (shocked nebular) X-ray emission. This nebula represents an excellent subject to investigate the molecular chemistry and physical conditions within photon- and X-ray-dominated regions (PDRs and XDRs). As yet, the exact formation routes of CO⁺and HCO⁺in PN environments remain uncertain. Here we present ∼2″ resolution maps of NGC 7027 in the irradiation tracers CO⁺and HCO⁺obtained with the IRAM NOEMA interferometer, along with SMA CO and HST 2.12μm H₂data for context. The CO⁺map constitutes the first interferometric map of this molecular ion in any PN. Comparison of CO⁺and HCO⁺maps reveals strikingly different emission morphologies, as well as a systematic spatial displacement between the two molecules; the regions of brightest HCO⁺, found along the central waist of the nebula, are radially offset by ∼1″ (∼900 au) outside the corresponding CO⁺emission peaks. The CO⁺emission furthermore precisely traces the inner boundaries of the nebula’s PDR (as delineated by near-IR H₂emission), suggesting that central star UV emission drives CO⁺formation. The displacement of HCO⁺radially outward with respect to CO⁺is indicative that dust-penetrating soft X-rays are responsible for enhancing the HCO⁺abundance in the surrounding molecular envelope, forming an XDR. These interferometric CO⁺and HCO⁺observations of NGC 7027 thus clearly establish the spatial distinction between the PDR and XDR formed (respectively) by intense UV and X-ray irradiation of molecular gas.