Discovery of an Edge-On Disk in the MBM 12 Young Association

We report the discovery of a spatially resolved edge-on protoplanetary disk in the ~2 Myr old MBM 12 young association. Our near-infrared images of LkHα 263C (MBM 12A 3C), obtained with the Hokupa`a adaptive optics system on the Gemini North telescope, clearly show two elongated reflection nebulosities separated by a dark lane, a morphology well matched by scattered-light models of an optically thick (at near-infrared wavelengths) edge-on disk. An optical spectrum of the scattered-light nebulosity obtained with the Keck II telescope exhibits a spectral type of M0 ± 0.5 (T_eff = 3850 ± 100 K) for the central star and contains Hα and forbidden emission lines, which may indicate the presence of a jet. The absence of a near-infrared point source implies A_K > 9.5 toward the unseen central star. The disk is flared and has a radius of ~150 AU (at a distance of 275 pc) and an inclination of 87°. The aspect ratio of the model disk in the J band is 0.72. There is possible evidence of dust settling to the disk midplane. LkHα 263C is 4115 from the 0415 binary LkHα 263 A and B (MBM 12A 3A and 3B), which is itself 155 from LkHα 262 (MBM 12A 2). Thus, LkHα 263C may be the first disk to be clearly resolved around an individual star in a young quadruple system. The detection of a faint edge-on disk near a bright star demonstrates both the high angular resolution and the high sensitivity that can be achieved with adaptive optics imaging on large telescopes.