Search Publications
Measurements of the Ca II infrared triplet emission lines of pre-main-sequence stars
Itoh, Yoichi; Takagi, Yuhei; Yamashita, Mai
We investigated the chromospheric activity of 60 pre-main-sequence (PMS) stars in four molecular clouds and five moving groups. It is considered that strong chromospheric activity is driven by the dynamo processes generated by stellar rotation. In contrast, several researchers have pointed out that the chromospheres of PMS stars are activated by m…
Investigation of contact binaries in the field of NGC 6811
Liu, Liang; Li, Xu-Zhi; Zhang, Xu-Dong
Contact binary systems are very important for studying physical processes such as strong interactions between stars, mass transfer, and stellar merger. Further, the members of an open cluster have the same age, metal abundance, and interstellar extinction conditions. Therefore, we can conduct a comparative study on the different binary systems of …
Performance of VERA in 10 micro-arcsecond astrometry
Hirota, Tomoya; Honma, Mareki; Nakagawa, Akiharu +9 more
Very Long Baseline Interferometry (VLBI) astrometry using the phase-referencing technique remains an open issue for the quantitative characterization of the observing conditions to achieve a feasible parallax precision of 10 micro-arcseconds (µas). To address this issue, we evaluated the astrometric performance of the VLBI Exploration of Rad…
X-ray properties of high-richness CAMIRA clusters in the Hyper Suprime-Cam Subaru Strategic Program field
Oguri, Masamune; Fujimoto, Ryuichi; Okabe, Nobuhiro +13 more
We present the first results of a pilot X-ray study of 37 rich galaxy clusters at 0.1 < z < 1.1 in the Hyper Suprime-Cam Subaru Strategic Program field. Diffuse X-ray emissions from these clusters were serendipitously detected in the XMM-Newton fields of view. We systematically analyze X-ray images of 37 clusters and emission spectra of a su…
BC Cassiopeiae: First detection of IW Andromedae-type phenomenon among post-eruption novae
Kato, Taichi; Kojiguchi, Naoto
IW And-type dwarf novae are a recently recognized group of cataclysmic variables which are characterized by a sequence of brightening from a standstill-like phase with damping oscillations often followed by a deep dip. We found that the supposed classical nova BC Cas which erupted in 1929 experienced a state of an IW And-type dwarf nova in 2018, 8…
HCN 3-2 survey towards a sample of local galaxies
Fang, Min; Li, Shanghuo; Wang, Junzhi +4 more
We present observations of HCN 3-2 emissions towards 37 local galaxies using the 10 m Submillimeter Telescope. HCN 3-2 emission is detected in 23 galaxies. The correlation of infrared luminosity (LIR) and the luminosity of HCN 3-2 line emission measured in our sample is fitted with a slope of 1.11 and correlation coefficient of 0.91, wh…
Gaia DR2 data and the evolutionary status of eight high-velocity hot post-AGB candidates
Matsuno, Tadafumi; Aoki, Wako; Parthasarathy, Mudumba
From Gaia DR2 data of eight high-velocity hot post-AGB candidates, LS 3593, LSE 148, LS 5107, HD 172324, HD 214539, LS IV -12 111, LS III +52 24, and LS 3099, we found that six of them have accurate parallaxes which made it possible to derive their distances, absolute visual magnitudes (MV) and luminosity (log L/L⊙). All the …
Discovery of radio jets in the Phoenix galaxy cluster center
Kohno, Kotaro; Oguri, Masamune; Kawabe, Ryohei +6 more
We report the results of the Australia Telescope Compact Array (ATCA) 15 mm observation of the Phoenix galaxy cluster possessing an extreme star-burst brightest cluster galaxy (BCG) at the cluster center. We spatially resolved radio emission around the BCG, and found diffuse bipolar and bar-shape structures extending from the active galactic nucle…
Detection of tidal tails around the open cluster M 67 using principal component analysis
Gao, Xinhua
In this paper we present an investigation of tidal tails around the old open cluster M 67 using Gaia-DR2. We identify likely extra-tidal stars around M 67 using principal component analysis (PCA) and a Gaussian mixture model (GMM). We find 1618 stars closely related to M 67, 85 of which are likely extra-tidal stars. We find clear evidence for the …
First detection of X-ray line emission from Type IIn supernova 1978K with XMM-Newton's RGS
Katsuda, Satoru; Takahashi, Koh; Yoshida, Takashi +2 more
We report on robust measurements of elemental abundances of the Type IIn supernova SN 1978K, based on the high-resolution X-ray spectrum obtained with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton. The RGS clearly resolves a number of emission lines, including N Ly $\alpha$ , O Ly $\alpha$ , O Ly $\beta$ , Fe xvii, Fe xviii, Ne He $…