Hubble 12 (Hb 12) is a bipolar planetary nebula with an hourglass like shape. The nebula has three pairs of bipolar lobes. Hb 12 was discovered by American astronomer Edwin Hubble in 1921. Hb 12 has three pairs of bipolar lobes with a faint Hα arc filament. The outermost lobe is fainter on the eastern side than on the western side, which indicates less dense regions on the eastern side of the PN. The distance of Hb 12 is estimated to be ~2.24 kpc to ~14.25 kpc. The zone with a high electron density of ~5x10⁵ cm-3 corresponds to an electron temperature of ~13,600 K. A shocked Fe II line was found near the core of the bipolar structure.
Central Star Central star of Hb 12 has an estimated temperature of ~35,000 K and a luminosity of ~1200 L⊙. The appearance of highly structured bipolar lobes with two pairs of H² knots suggests that multiple pulsed mass-loss episodes have occurred during the AGB or post-AGB phases.
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