Humason 1-2 (Hu 1-2) is a bipolar hourglass shaped planetary nebula. Hu 1-2 was discovered by astronomer Milton L. Humason in October 11, 1920. The distance of Hu 1-2 has never been confirmed, One study gave a lower limit of ~1.17 kpc, but the galactocentric distance might be ~9 kpc, estimated from ~3.5 kpc. The nebula is 8.8° above the plane, corresponding to 150-300 pc. A study identified two bipolar knots moving at velocities greater than 340 kms-1. These knots were found to contain N II and O III emission lines, the N II line seems to get larger when it is further from the central star than the O III line. The N II emission in the knots implies shock-excitation, while the O III emissions are more like irradiation. The kinematical structure of the faint bipolar lobes remains completely unknown, but the lobes have an inclination of ≤10° and a polar expansion velocity of ~150 kms-1, resulting in a lower-limit expansion age of ≤1100 yr. The high abundance of He/H and N/O ratios of the bright inner reigons of Hu 1-2 suggest it is a Type I PN, though analysis found abundances of α elements. Hu 1-2 could be a halo PN, but this is unconfirmed. The nebula is enriched in α elements, especially hydrogen and helium. The NW structure/knot shows O II/O III and He II/Hα ratios than those typically seen in the low-ionization structures and outflows of other PNe.
The central star Type I nature of the nebula indicates that the star descended from a massive intermediate-mass progenitor star, or the abundances of α elements may be a result of a formation of a massive PN progenitor from metal-poor materials.
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