SIMBAD references

We present high spatial resolution (≈ 60-90 mas) images of the molecular hydrogen emission in the planetary nebula (PN) NGC 2346. The data were acquired during the system verification of the Gemini Multi-conjugate Adaptive Optics System + Gemini South Adaptive Optics Imager. At the distance of NGC 2346, 700 pc, the physical resolution corresponds to ≈ 56 AU, which is slightly higher than an [N ii] image of NGC 2346 that was obtained with the Hubble Space Telescope/WFPC2. With this unprecedented resolution, for the first time we were able to study the structure of the H₂ gas within the nebula in detail. We found it to be composed of knots and filaments, which at a lower resolution had appeared to be a uniform torus of material. We explain how the formation of the clumps and filaments in this PN are consistent with a mechanism in which a central hot bubble of nebular gas surrounding the central star has been depressurized, and the thermal pressure of the photoionized region drives the fragmentation of the swept-up shell.