Direct Detection of the Mira at the Heart of OH 231.8+4.2

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Abstract
The evolved bipolar nebula OH 231.8+4.2 is host to a Mira variable star, QX Pup, at its core. We used the diffraction-limited near-infrared imaging (DLIRIM) system at Kitt Peak to obtain the first direct images of this star in the near-infrared. In subarcsecond resolution DLIRIM images at K (2.2 μm) and L' (3.8 μm) the star is clearly detected and is well resolved from the surrounding nebulosity. The star lies midway between the lobes of the OH 231.8+4.2 reflection nebula, confirming previous inferences based on polarimetric imaging and nebular colors. In addition to betraying the location of the central Mira, these images reveal the detailed structure of OH 231.8+4.2, including a point symmetric system of jetlike features protruding from its polar lobes. The K - L' color distribution of the nebula is consistent with reflection and extinction of near-infrared radiation from the Mira by dust grains larger than those characteristic of the interstellar medium. From the apparent K magnitude of the star, combined with its relatively well-determined distance (1300 pc) and the circumstellar extinction we infer from its measured K - L' color, we estimate a mean absolute magnitude MK ~ -10.2, comparable to Mira variables of similar (~700 day) period in the Large Magellanic Cloud. In this and other respects, the central Mira appears remarkably "normal" given its position at the heart of such an unusual object.