Subaru/HiCIAO $H{K}_{\mathrm{s}}$ imaging of LkH$\alpha$ 330 - multi-band detection of the gap and spiral-like structures

Abstract

We present $H$- and $K_{\mathrm{s}}$-bands observations of the LkH$\alpha$ 330 disk with a multi-band detection of the large gap and spiral-like structures. The morphology of the outer disk ($r\sim$$0\farcs3$) at PA=0--45${}^{\circ }$ and PA=180--290${}^{\circ }$ are likely density wave-induced spirals and comparison between our observational results and simulations suggests a planet formation. We have also investigated the azimuthal profiles at the ring and the outer-disk regions as well as radial profiles in the directions of the spiral-like structures and semi-major axis. Azimuthal analysis shows a large variety in wavelength and implies that the disk has non-axisymmetric dust distributions. The radial profiles in the major-axis direction (PA=$271^{\circ }$) suggest that the outer region ($r\geq0\farcs25$) may be influenced by shadows of the inner region of the disk. The spiral-like directions (PA=10${}^{\circ }$ and 230${}^{\circ }$) show different radial profiles, which suggests that the surfaces of the spiral-like structures are highly flared and/or have different dust properties. Finally, a color-map of the disk shows a lack of an outer eastern region in the $H$-band disk, which may hint the presence of an inner object that casts a directional shadow onto the disk.

12pages, 16 figures, 2 tables, accepted for publication in AJ