A Circumstellar Disk around HD 169142 in the Mid-Infrared (N-Band)

The Herbig Ae star HD 169142 is one of the objects that show complex structure, such as multiple (innermost, middle, and outer) disks, gaps, and unresolved sources. We made N-band (8–13 μm) observations of HD 169142 with the Cooled Mid-Infrared Camera and Spectrometer on the 8.2 m Subaru Telescope. The images are spatially resolved out to an ∼1″ radius in all the observed bands. We made a simple disk model composed of an unresolved central source (representing the innermost disk/halo) and the ring at a radius r ∼ 25 au (corresponding to the inner wall or edge of a middle disk at ∼25–40 au). The radial intensity profile within the central region (≲0.″3 or $\lesssim 40$ au) is well reproduced by the model. Furthermore, we subtracted the model image from the observed one to search for additional structures. In the model-subtracted images, we found an unresolved west source separated by 17.0 ± 2.9 au in the direction of position angle 260° ± 5° from the original emission peak, which is supposed to correspond to the position of the central star, and a bright east arc located at r ∼ 60 au. The west source is different from the L′-band unresolved source recently found in coronagraphic observations. It could be a structure related to planet formation in the disk, such as a circumplanetary disk or clumpy disk structure. The east arc corresponds to the inner wall or edge of the outer disk.