ALMA Observation of the Protoplanetary Disk Around HD 163296

Abstract

We have conducted the water line observations for the protoplanetary disk around the Herbig Ae star HD 163296, and partial data were delivered. We analyzed the upper limit fluxes of sub-millimeter ortho-H$_{2}$ $^{16}$O 321 GHz, para-H$_{2}$ $^{18}$O 322 GHz, and HDO 335 GHz lines, which are considered to be the best candidate water lines available at sub-millimeter wavelengths to locate the $\mathrm {H_2O}$ snowline positions, according to our previous model studies. We compared the upper limit fluxes with the values obtained using our models with dust emission, and constrained the line emitting region and the dust opacity from observations. We concluded that, if the outer edge of the water vapor abundant region and also the water snowline position is beyond 8 au, the 1 mm dust opacity $\kappa _{\mathrm {mm}}$ will have a value larger than 2.0 cm$^{2}$ g$^{-1}$. Moreover, if $\kappa _{\mathrm {mm}}$ is 2.0 cm$^{2}$ g$^{-1}$, the water snowline position will be inside 20 au. The multiple gap and ring structures in 0.9 mm (Band 7) dust continuum emission with the spatial resolution of 15 au are also reported. The gap and ring positions are consistent with those estimated in the previous observations. Most contents of this chapter is based on our refereed paper that has been published (Notsu et al. 2019, ApJ, 875, 96).