Distribution and Kinematics of H I through Raman He II Spectroscopy of NGC 6302

The young planetary nebula NGC 6302 is known to exhibit Raman-scattered He II features at 6545 and 4851 Angstrom. These features are formed through inelastic scattering of He II$\lambda\lambda$ 1025 and 972 with hydrogen atoms in the ground state, for which the cross sections are $1.2 \times 10^{-21}$ and $1.4\times 10^{-22} {\rm\ cm^2}$, respectively. We investigate the spectrum of NGC 6302 archived in the ESO Science Portal. Our Gaussian line fitting analysis shows that the Raman-scattered He II features are broader and more redshifted than the hypothetical model Raman features that would be formed in a cold static H I medium. We adopt a simple scattering geometry consisting of a compact He II emission region surrounded by a H I medium to perform Monte Carlo simulations using the radiative transfer code ${\it STaRS}$. Our simulations show that the H I region is characterized by the H I column density $N_{\rm HI}=3\times 10^{21}{\rm\ cm^{-2}}$ with the random speed component $v_{\rm ran}=10{\rm\ km\ s^{-1}}$ expanding with a speed $v_{\rm exp}= 13{\rm\ km\ s^{-1}}$from the He II emission region. Based on our best fit parameters, we estimate the H I mass of the neutral medium$M_{\rm HI} \simeq 1.0\times 10^{-2}\ {\rm M_\odot}$, pointing out the usefulness of Raman He II spectroscopy as a tool to trace H I components.Comment: 12 pages, 8 figures, accepted for publication in Ap

First Detection and Modeling of Spatially Resolved Lyα\alpha in TW Hya

Lyman-$\alpha$ (Ly$\alpha$) is the strongest emission line in UV spectra from T-Tauri stars. Due to its resonant nature, Ly$\alpha$ emission carries information about the physical properties of the H I medium via the scattering process. This work presents spatially resolved Ly$\alpha$ emission across a protoplanetary disk in the iconic face-on T-Tauri star TW Hya, observed with HST-STIS at spatial offsets 0$''$, $\pm 0.2''$, and $\pm 0.4''$. To comprehensively interpret these Ly$\alpha$ spectra, we utilize a 3D Monte-Carlo radiative transfer simulation in a wind-disk geometry. Successfully reproducing the observed spectra requires scattering contributions from both the wind and the H I disk. We constrain the properties of the wind, the H I column density ($\sim 10^{20} \rm cm^{-2}$) and the outflow velocity ($\sim 200 \rm km s^{-1}$). To reproduce the observed spatial distribution of Ly$\alpha$, we find that the wind must cover the H I disk when viewed face-on. Furthermore, to explore the effect of Ly$\alpha$ radiative transfer in T-Tauri stars, we compute the radiation field within the scattering medium and reveal that the wind reflection causes more Ly$\alpha$ photons to penetrate the disk. We also show the dependence between the disk inclination angle and the spatially resolved Ly$\alpha$ spectra. Understanding the role of Ly$\alpha$ emission in T-Tauri stars is pivotal for decoding the complex interactions between the winds, protoplanetary disks, and surrounding environments, which can significantly impact the chemistry in the protoplanetary disk. Our observation and modeling of spatially resolved Ly$\alpha$ show the necessity of spatially resolved Ly$\alpha$ observation of a broad range of targets.Comment: 17 pages, 18 figures, Submitted to MNRA

Radiative Transfer in Ly{\alpha} Nebulae: I. Modeling a Continuous or Clumpy Spherical Halo with a Central Source

To understand the mechanism behind high-$z$ Ly${\alpha}$ nebulae, we simulate the scattering of Ly${\alpha}$ in a $\rm H\,I$ halo about a central Ly${\alpha}$ source. For the first time, we consider both smooth and clumpy distributions of halo gas, as well as a range of outflow speeds, total $\rm H\,I$ column densities, $\rm H\,I$ spatial concentrations, and central source galaxies (e.g., with Ly${\alpha}$ line widths corresponding to those typical of AGN or star-forming galaxies). We compute the spatial-frequency diffusion and the polarization of the Ly${\alpha}$ photons scattered by atomic hydrogen. Our scattering-only model reproduces the typical size of Ly${\alpha}$ nebulae ($\sim 100\,$kpc) at total column densities $N_{\rm HI} \geq 10^{20} \rm cm^{-2}$ and predicts a range of positive, flat, and negative polarization radial gradients. We also find two general classes of Ly${\alpha}$ nebula morphologies: with and without bright cores. Cores are seen when $N_{\rm HI}$ is low, i.e., when the central source is directly visible, and are associated with a polarization jump, a steep increase in the polarization radial profile just outside the halo center. Of all the parameters tested in our smooth or clumpy medium model, $N_{\rm HI}$ dominates the trends. The radial behaviors of the Ly${\alpha}$ surface brightness, spectral line shape, and polarization in the clumpy model with covering factor $f_c \gtrsim 5$ approach those of the smooth model at the same $N_{\rm HI}$. A clumpy medium with high $N_{\rm HI}$ and low $f_c \lesssim 2$ generates Ly${\alpha}$ features via scattering that the smooth model cannot: a bright core, symmetric line profile, and polarization jump.Comment: 42 pages, 27 figures, accepted for publication in ApJ, Comments welcome

Tracing the historical origin of Joseon mummies considering the structural similarities between the burial systems of Korean and Chinese dynasties

Joseon mummies have proved to be excellent subjects for scientific research on the health and disease statuses of pre-modern Korean peoples. Despite its academic significance, the origins of the Hoegwakmyo tomb in which the Joseon mummy was discovered have not yet been entirely revealed. Meanwhile, over the past several decades, there have been some reports on mummies and cultural artifacts preserved very well in the tombs of several Chinese dynasties (especially Song, Yuan, Ming and Qing). Although the Chinese tombs were very diverse in structure, we note that some graves among them were structurally very similar to Joseon Hoegwakmyo tombs. Before the Hoegwakmyo tomb in Korea, there were already similar tombs in China, inside which dead persons were mummified like the Joseon mummies. Considering that the Hoegwakmyo tomb of the Joseon Dynasty was established by the influence of the Confucian ideology, the Korean and Chinese mummies might share common cultural origins in history