We have analyzed the OCS, H 2 CS, CH 3 OH, and HCOOCH 3 data observed toward the low-mass protostar IRAS 16293-2422 Source B at a sub-arcsecond resolution with ALMA. A clear chemical differentiation is seen in their distributions; OCS and H 2 CS are extended with a slight rotation signature, while CH 3 OH and HCOOCH 3 are concentrated near the protostar. Such a chemical change in the vicinity of the protostar is similar to the companion (Source A) case. The extended component is interpreted by the infalling-rotating envelope model with a nearly face-on configuration. The radius of the centrifugal barrier of the infalling-rotating envelope is roughly evaluated to be (30 − 50) au. The observed lines show the inverse P-Cygni profile, indicating the infall motion with in a few 10 au from the protostar. The nearly pole-on geometry of the outflow lobes is inferred from the SiO distribution, and thus, the infalling and outflowing motions should coexist along the line-of-sight to the protostar. This implies thatthe infalling gas is localized near the protostar and the current launching points of the outflow have an offset from the protostar. A possible mechanism for this configuration is discussed.

Understanding the inner structure of the clumpy molecular torus surrounding the active galactic nucleus is essential in revealing the forming mechanism. However, spatially resolving the torus is difficult because of its size of a few parsecs. Thus, to probe the clump conditions in the torus, we performed the velocity decomposition of the CO rovibrational absorption lines (Δv = 0 →1, ΔJ = ±1) at λ ∼ 4.67 μm observed toward an ultraluminous infrared galaxy IRAS 08572+3915 NW with the high-resolution spectroscopy (R ∼ 10,000) of Subaru Telescope. Consequently, we found that each transition had two outflowing components, i.e., (a) and (b), both at approximately ∼−160 km s−1, but with broad and narrow widths, and an inflowing component, i.e., (c), at approximately ∼+100 km s−1, which were attributed to the torus. The ratios of the velocity dispersions of each component led to those of the rotating radii around the black hole of R rot,a: R rot,b: R rot,c ≈ 1: 5: 17, indicating the torus where clumps are outflowing in the inner regions and inflowing in the outer regions if a hydrostatic disk with σ V ∝ R rot − 0.5 is assumed. Based on the kinetic temperature of components (a) and (b) of ∼720 and ∼25 K, respectively, estimated from the level population, the temperature gradient is T kin ∝ R rot − 2.1 . Magnetohydrodynamic models with large density fluctuations of two orders of magnitude or more are necessary to reproduce this gradient.

The ultraluminous infrared galaxy IRAS 17208−0014 is a late-stage merger that hosts a buried active galactic nucleus (AGN). To investigate its nuclear structure, we performed high-spatial-resolution ( ∼ 0.″04 ∼ 32 pc) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 9 (∼450 μm or ∼660 GHz), along with near-infrared AKARI spectroscopy in 2.5–5.0 μm. The Band 9 dust continuum peaks at the AGN location, and toward this position CO(J = 6 − 5) and CS(J = 14 − 13) are detected in absorption. Comparison with nonlocal thermal equilibrium calculations indicates that, within the central beam (r ∼ 20 pc), there exists a concentrated component that is dense (107 cm−3) and warm (>200 K) and has a large column density ( N H 2 > 10 23 cm − 2 ). The AKARI spectrum shows deep and broad CO rovibrational absorption at 4.67 μm. Its band profile is well reproduced with a similarly dense and large column but hotter (∼1000 K) gas. The region observed through absorption in the near-infrared is highly likely in the nuclear direction, as in the submillimeter, but with a narrower beam including a region closer to the nucleus. The central component is considered to possess a hot structure where vibrationally excited HCN emission originates. The most plausible heating source for the gas is X-rays from the AGN. The AKARI spectrum does not show other AGN signs in 2.5–4 μm, but this absence may be usual for AGNs buried in a hot mid-infrared core. Further, based on our ALMA observations, we relate the various nuclear structures of IRAS 17208−0014 that have been proposed in the literature.