We present the results of high resolution (R≥30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in optical/near-IR with the BOES, HET-HRS, and IGRINS spectrographs, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first two years. The Half-Width at Half-Depth (HWHD) of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s −1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s −1 . Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R ⊙ , respectively.We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

We present a library of high-resolution (R ≡ λ/∆λ ∼ 45,000) and high signal-to-noise ratio (S/N ≥ 200) near-infrared spectra for stars of a wide range of spectral types and luminosity classes. The spectra were obtained with the Immersion GRating INfrared Spectrograph (IGRINS) covering the full range of the H (1.496-1.780 µm) and K (2.080-2.460 µm) atmospheric windows. The targets were primarily selected for being MK standard stars covering a wide range of effective temperatures and surface gravities with metallicities close to the Solar value. Currently, the library includes flux-calibrated and telluric-absorption-corrected spectra of 84 stars, with prospects for expansion to provide denser coverage of the parametric space. Throughout the H and K atmospheric windows, we 2 Park et al.identified spectral lines that are sensitive to T eff or log g and defined corresponding spectral indices.We also provide their equivalent widths. For those indices, we derive empirical relations between the measured equivalent widths and the stellar atmospheric parameters. Therefore, the derived empirical equations can be used to calculate T eff and log g of a star without requiring stellar atmospheric models.

Chytridiomycosis, a disease that has caused amphibian population declines globally and elevated many species of anurans to endangered or threatened status, has recently been declared an internationally notifiable disease. Batrachochytrium dendrobatidis (Bd), the amphibian chytrid fungus causing this disease, has not been previously reported in Korea or on mainland Asia. Thirty-six frog specimens representing 7 species were collected from the wild in South Korea and examined for Bd using standard PCR. Bd was detected in 14 (38.8%) samples from 3 species (Bufo gargarizans, Hyla japonica, and Rana catesbiana). Skin sections from all 14 PCR-positive frogs were examined using 2 staining techniques: haematoxylin and eosin (H&E) and Bd immunoperoxidase (IPX). In histological sections, zoosporangia were found in 6 frogs, with lower sensitivity for H&E (21%) than for IPX (46%). Intensity of infection, based on histopathology, was low in all frogs. These results confirm that Bd is present in South Korea and, hence, on the Asian mainland. Studies are urgently required to determine the impact of chytridiomycosis on Korean amphibians, and to map the distribution of Bd in Korea and other Asian mainland countries. KEY WORDS: Chytridiomycosis · Batrachochytrium dendrobatidis · Amphibian decline · Korea · Fungus Resale or republication not permitted without written consent of the publisherDis Aquat Org 86: [9][10][11][12][13] 2009 nerable (Matsui 2004), and Hynobius yangi is classified as endangered (Stuart 2008) MATERIALS AND METHODSFrogs were collected opportunistically from the northern part of South Korea between June 11 and December 13, 2007 (see Table 1). During nocturnal and occasional diurnal surveys, frogs were captured individually by hand, with a new pair of disposable latex gloves being used for each frog in order to avoid cross-contamination between individuals . The animals were sacrificed by soaking them in a bath of 0.05% aqueous tricaine methane sulfonate (MS-222). We aseptically cut small pieces of skin from the abdomen, inguinal region, and web between toes; we then divided this into 2, and placed 1 in 10% formalin for histological analysis and the other in a 1.5 ml microtube for DNA extraction. Instruments were flamed after dissection of each specimen to prevent cross-contamination. DNA was immediately extracted with Gene Releaser (Bio Ventures). The PCR assay used species-specific primers (Bd1a and Bd2a) located within internal transcribed spacer ITS1 and ITS2 to amplify the 5.8S region of nuclear rDNA (Annis et al. 2004). The PCR products were examined using 1.0% agarose gel and some of the positive bands were cut and sequenced to confirm the Bd sequence. Each sample was tested in triplicate, and was only recorded as positive if all 3 replicates indicated the presence of Bd. For PCR positive amphibians, histological sections of formalin fixed skin were stained using 2 techniques: haematoxylin and eosin (H&E) and Bd immunoperoxidase (IPX), the latter technique using polyclonal antibodies speci...

Stellar kinematics provides the key to understanding the formation process and dynamical evolution of stellar systems. Here, we present a kinematic study of the massive star-forming region (SFR) W4 in the Cassiopeia OB6 association using the Gaia Data Release 2 and high-resolution optical spectra. This SFR is composed of a core cluster (IC 1805) and a stellar population distributed over 20 pc, which is a typical structural feature found in many OB associations. According to a classical model, this structural feature can be understood in the context of the dynamical evolution of a star cluster. The core-extended structure exhibits internally different kinematic properties. Stars in the core have an almost isotropic motion, and they appear to reach virial equilibrium given their velocity dispersion (0.9 ± 0.3 km s−1) comparable to that in a virial state (∼0.8 km s−1). On the other hand, the distributed population shows a clear pattern of radial expansion. From the N-body simulation for the dynamical evolution of a model cluster in subvirial state, we reproduce the observed structure and kinematics of stars. This model cluster experiences collapse for the first 2 Myr. Some members begin to radially escape from the cluster after the initial collapse, eventually forming a distributed population. The internal structure and kinematics of the model cluster appear similar to those of W4. Our results support the idea that the stellar population distributed over 20 pc in W4 originate from the dynamical evolution of IC 1805.

Stellar kinematics is a powerful tool for understanding the formation process of stellar associations. Here, we present a kinematic study of the young stellar population in the Rosette nebula using recent Gaia data and high-resolution spectra. We first isolate member candidates using the published mid-infrared photometric data and the list of X-ray sources. A total of 403 stars with similar parallaxes and proper motions are finally selected as members. The spatial distribution of the members shows that this star-forming region is highly substructured. The young open cluster NGC 2244 in the center of the nebula has a pattern of radial expansion and rotation. We discuss its implication on the cluster formation, e.g., monolithic cold collapse or hierarchical assembly. On the other hand, we also investigate three groups located around the border of the H ii bubble. The western group seems to be spatially correlated with the adjacent gas structure, but their kinematics is not associated with that of the gas. The southern group does not show any systematic motion relative to NGC 2244. These two groups might be spontaneously formed in filaments of a turbulent cloud. The eastern group is spatially and kinematically associated with the gas pillar receding away from NGC 2244. This group might be formed by feedback from massive stars in NGC 2244. Our results suggest that the stellar population in the Rosette Nebula may form through three different processes: the expansion of stellar clusters, hierarchical star formation in turbulent clouds, and feedback-driven star formation.