Search Publications
Near-Infrared Spectra of 21 Wolf-Rayet Stars: Wind Clumping and Mass-Loss Rates
Miyata, Takashi; Motohara, Kentaro; Nishimaki, Yuichirou +2 more
We present 0.9-2.4µm spectra of 21 galactic Wolf-Rayet (WR) stars that were obtained by using an echelle spectrograph attached to the 1.5m infrared telescope in Tokyo. The observed Wolf-Rayet stars contain 12WNE, 3WNL, and 6WC stars. The near-infrared continuum spectra can be fitted by the superposition of stellar blackbody radiation with a …
Spatial Distributions of Dust and Polycyclic Aromatic Hydrocarbons in the Nearby Elliptical Galaxy NGC 4589 Observed with AKARI
Onaka, Takashi; Sakon, Itsuki; Kaneda, Hidehiro +2 more
We report on near- to far-infrared (IR) observations of the nearby elliptical galaxy NGC 4589 by AKARI. NGC 4589 has acomplex stellar rotation field with aposition angle difference of 45° between the kinematic and morphological axes, although its morphology shows asmooth optical profile that closely follows the de Vaucouleurs law. The galaxy has a…
Implication for Super-Critical Accretion Flow in the Narrow-Line Seyfert 1 Galaxy PKS 0558-504
Kunieda, Hideyo; Haba, Yoshito; Terashima, Yuichi +1 more
We present results from XMM-Newton observations of the narrow-line Seyfert 1 galaxy PKS0558-504. The 2-12keV X-ray spectra can be well-reproduced by a single power law with a photon index of ∼2.2. The extrapolation of this power law continuum into the lower energy band reveals the existence of a strong soft excess component. When we applied a mult…
Suzaku Observation of the Anomalous X-Ray Pulsar CXOU J164710.2--455216
Dotani, Tadayasu; Enoto, Teruaki; Kokubun, Motohide +11 more
A Suzaku TOO observation of CXOU J164710.2-455216 was performed on 2006 September 23-24 for a net exposure of 38.8ks. Pulsations were clearly detected in the XIS light curves with a pulse period of 10.61063(2)s. The XIS pulse profile is found to be highly non-sinusoidal. It shows 3 peaks of different amplitudes with an RMS fractional amplitude of …
Suzaku Observations of the Cluster of Galaxies Abell 2052
Kunieda, Hideyo; Ohashi, Takaya; Mitsuda, Kazuhisa +7 more
The results from Suzaku X-ray Imaging Spectrometer (XIS) observations of relaxed cluster of galaxies, Abell 2052, are presented. Offset pointing data were used to estimate the Galactic foreground emission in the direction of the cluster. Significant soft X-ray excess emission above this foreground, the intracluster medium emission, and other backg…
Central Spiral Structure of Molecular Gas in Maffei 2
Kuno, Nario; Nakanishi, Kouichiro; Sorai, Kazuo +1 more
The distribution and kinematics of molecular gas in the central region of the barred spiral galaxy Maffei2 were investigated using a data set of 12CO(1-0),12CO(2-1), CS(2-1) lines, and 103GHz continuum. We found that the offset ridges along the kpc-scale bar continue to the central spiral structure embedded in a weak oval str…
XMM-Newton Observations of NGC 4051: Temporal Flux and Spectral Variability during Transition to the Faintest Phase in NGC 4051
Tsuruta, Sachiko; Liebmann, Andrew C.; Kunieda, Hideyo +2 more
We report on the results from temporal and spectral analyses of NGC 4051 observed with XMM-Newton. The X-ray variabilities in the higher-flux states are well explained by the combination of a variable, direct power law and a temporally stable, absorbed component. In low-flux states, however, spectral variations are mainly due to flux changes of th…
Suzaku Detection of an Intense X-Ray Flare from an A-Type Star, HD161084
Sugawara, Yasuharu; Maeda, Yoshitomo; Tsujimoto, Masahiro +4 more
We report on a serendipitous detection of an intense X-ray flare from the Tycho reference source on HD161084 during a Suzaku observation of the galactic center region for ∼20ks. The X-ray Imaging Spectrometer recorded a flare from this A1-type dwarf or subgiant star with a flux of ∼1.4 × 10-12 erg s-1 cm-2 (0.5--10…
Near-Infrared Coronagraphic Observations of a Classical TTauri Star, DO Taurus
Tamura, Motohide; Hayashi, Masahiko; Kudo, Tomoyuki +4 more
A high angular resolution near-infrared image of a classical TTauri star, DO Tau, was obtained with Coronagraphic Imager with Adaptive Optics (CIAO) mounted on the Subaru Telescope. Circumstellar emission was detected at ∼1".7 from the central star in the direction of the redshifted jet. No emission was found toward the opposite direction. We also…
Identification of the Exciting Source of CO Outflow in the Star-Formation Region GGD 12-15
Tamura, Motohide; Hashimoto, Jun; Kudo, Tomoyuki +10 more
We present results of near-infrared imaging polarimetry of the GGD 12-15 region with the IRSF 1.4m telescope and the SIRIUS camera/SIRPOL polarimeter and mid-infrared imaging with the AKARI telescope and the Infra-Red Camera (IRC). Two infrared sources, IRS9E and IRS9M near an H2O maser source situated on both sides around a VLA source …