Hydrogen Molecules in the Planetary Nebula NGC6302

NGC 6302 is the classical example of a planetary nebula with a bipolar shape. The bipolar ‘butterfly’ shape is often explained as caused by the fast wind of the central star colliding with a dense circumstellar disk. This disk should be compressible, i.e., molecular. The main constituent will be hydrogen molecules. H2 lines have been detected with ISO/SWS in NGC6302, covering the wavelength range 2 17 μm. The energy diagram of these lines shows a thermal population of 700 900 K. The expected temperature of H2 in the disk is 100 K or less. We conclude that the detected H2 should be located on the surface of the disk, and most of H2 in the cold disk is not detected. There is some indication of colder H2 seen in the 17 μm line. Further mid-infrared observations are desired.