The Bug Nebula, NGC 6302, in Scorpius, is one of the most interesting and complex planetary nebulae in the sky.
NGC 6302 has been known since at least 1888, as it is included in the New General Catalogue. The earliest known study of NGC 6302 is by E. E. Barnard who drew and described it in 1907.
The nebula has a photographic magnitude of 13, and an apparent diameter of 0.8 arc minutes. It has a complex bipolar morphology with two primary lobes, similar to an hour-glass in shape. A dark lane runs through the waist of the nebula, obscuring the central star at visible wavelengths.
NGC 6302 lies about 4,000 light-years away. The spectrum of NGC 6302 shows that its central star is exceptionally hot, with an estimated surface temperature of about 250,000 degrees C. It must have been very large. It shines brightly in ultraviolet light, but has never been observed visually. It is hidden from direct view by dense equatorial torus of dust. Cutting across the bright ionized gas, the dust torus surrounding the central star is nearly edge-on to our line of sight.
This dense dust disc has caused the star's outflows to form their complex bipolar structure, with ionization walls, knots, and sharp edges. The prominent northwest lobe, which extends up to 3' away from the central star, is thought to have formed from an eruptive event around 1,900 years ago. At an angular distance of 1.71' from the central star, the flow velocity of this lobe is 263 km/sec. At the extreme periphery of the lobe, the outward velocity exceeds 600 km/sec. The western edge of the lobe suggests a collision with pre-existing globules of gas which modified the outflow in that region. There is evidence for a second pair of lobes that may have belonged to a previous phase of mass loss.
The prominent dark dust lane running through the center of the nebula shows extraordinary chemistry, including multiple crystalline silicates, carbonates, water ice, and quartz. The dust is both oxygen-rich and carbon-rich, indicative of a recent change from O-rich chemistry to C-rich chemistry in the central star. Molecular hydrogen has also been detected in this hot star's dusty cosmic shroud.