Seimei KOOLS-IFU mapping of the gas and dust distributions in Galactic planetary nebulae: the case of IC 2165

Abstract

ABSTRACT We investigated the physical and chemical properties of the gas and dust components in a carbon-rich planetary nebula (PN) IC 2165 using two-dimensional emission-line maps with superior resolution. The extinction map is generated in a self-consistent and assumption-free manner. The circumstellar gas-to-dust mass ratio (GDR) map ranges radially from 1210 in the central nebula filled with hot gas plasma to 120 near the ionization front. The determined GDR is comparable to ∼400, which is commonly adopted for carbon-rich asymptotic giant branch (AGB) stars, and ∼100 for interstellar medium. Except for the inner regions, the GDR in IC 2165 is nearly the same as in such AGB stars, indicating that most dust grains withstand the harsh radiation field without being destroyed. The gas and dust mass distributions concentrated in the equatorial plane may be related to the non-isotropic mass loss during the AGB phase and nebula shaping. The spatial distributions of electron densities/temperatures and ionic/elemental abundances were investigated herein. We determined 13 elemental abundances using point-spread-function-matched spatially integrated multiwavelength spectra extracted from the same aperture. Their values are consistent with values predicted by a theoretical model for stars of initially 1.75 M⊙ and Z = 0.003. Finally, we constructed the photoionization model using our distance measurement to be consistent with all derived quantities, including the GDR, gas and dust masses, and post-AGB evolution. Thus, we demonstrate the capability of the Kyoto Okayama Optical Low-dispersion Spectrograph with optical-fibre Integral Field Unit (KOOLS-IFU) and how the spatial variation of the gas and dust components in PNe derived from IFU observations can help understand the evolution of the circumstellar/interstellar medium.