SIMBAD references

High-resolution (0".15) 2.12 µm H₂and narrowband K images have been obtained of one cool proto-planetary nebula, IRAS 20028+3910, and two hot proto-planetary/young planetary nebulae, IRAS 19306+1407 and IRAS 22023+5249. The observations were made with an adaptive optics system and near-infrared imager on the Gemini North 8 m telescope. All three nebulae are seen to be extended, and in two and possibly all three of them H₂is found to be emitting from bipolar lobes. In IRAS 19306+1407, H₂emission is seen arising from a ring close to the star and from the edges of emerging bipolar lobes. In IRAS 20028+3910, one bright lobe and a very faint second lobe are seen in the H₂and K-band images, similar to the published visible images, but in the H₂and K-band images a faint filament appears to connect the two lobes. The central star is not seen in IRAS 20028+3910, indicating that the nebula is optically thick even at 2 µm, which is unusual. The images suggest that extended H₂emission is often the manifestation of fast-slow wind interactions in the bipolar lobes.