Search Publications
Localized recombining plasma in G166.0+4.3: A supernova remnant with an unusual morphology
Uchida, Hiroyuki; Nobukawa, Masayoshi; Tsuru, Takeshi Go +4 more
We observed the Galactic mixed-morphology supernova remnant G166.0+4.3 with Suzaku. The X-ray spectrum in the western part of the remnant is well represented by a one-component ionizing plasma model. The spectrum in the northeastern region can be explained by two components. One is an Fe-rich component with electron temperature kT_e = 0.87_{-0.03}…
A systematic X-ray study of the dwarf novae observed with Suzaku
Tsujimoto, Masahiro; Hayashi, Takayuki; Wada, Qazuya +1 more
X-ray behavior of the dwarf novae (DNe) outside the quiescent state has not been fully understood. We thus assembled 21 data sets of the 15 DNe observed by the Suzaku satellite by the end of 2013, which include spectra taken during not only the quiescence, but also the transitional, outburst, and super-outburst states. Starting with the traditiona…
Discovery of a keV-X-ray excess in RX J1856.5-3754
Yoneyama, Tomokage; Hayashida, Kiyoshi; Nakajima, Hiroshi +2 more
RX J1856.5-3754 is the brightest and nearest (∼120 pc) source among thermally emitting isolated neutron stars. Its spectra observed with XMM-Newton and Chandra satellites are well-fitted with the two-temperature (kT∞ ∼ 32 and 63 eV) blackbody model. Fitting ten sets of the data from Suzaku XIS 0, XIS 1, XIS 3, and XMM-Newton EPIC-pn wit…
Does the radial-tangential macroturbulence model adequately describe the spectral line broadening of solar-type stars?*
Takeda, Yoichi; UeNo, Satoru
In incorporating the effect of atmospheric turbulence in the broadening of spectral lines, the so-called radial-tangential macroturbulence (RTM) model has been widely used in the field of solar-type stars, which was devised from intuitive appearance of the granular velocity field of the Sun. Since this model assumes that turbulent motions are rest…
The mass-metallicity relation of AKARI-FMOS infrared galaxies at z ∼ 0.88 in the AKARI North Ecliptic Pole Deep Survey Field
Goto, Tomotsugu; Pearson, Chris; Matsuhara, Hideo +2 more
The mass, metallicity, and star formation rate (SFR) of a galaxy are crucial parameters in understanding galaxy formation and evolution. However, the relation between these parameters, (i.e., the fundamental relation) is still a matter of debate for luminous infrared (IR) galaxies, which carry a bulk of the SFR budget of the universe at z ∼ 1. We …
Search for the warm-hot intergalactic medium around A 2744 using Suzaku
Finoguenov, Alexis; Akamatsu, Hiroki; Ota, Naomi +2 more
We present the results from Suzaku satellite observations of the surrounding region of a galaxy cluster, A 2744, at z = 0.3. To search for oxygen emission lines from the warm-hot intergalactic medium (WHIM), we analyzed X-ray spectra from two northeastern regions 2.2-3.3 and 3.3-4.4 Mpc from the center of the cluster, which offers the first test o…
Validation of a scaling law for the coronal magnetic field strength and loop length of solar and stellar flares
Namekata, Kosuke; Shibata, Kazunari; Watanabe, Kyoko +2 more
Shibata and Yokoyama (1999, ApJ, 526, L49; 2002, ApJ, 577, 422) proposed a method of estimating the coronal magnetic field strength (B) and magnetic loop length (L) of solar and stellar flares, on the basis of magnetohydrodynamic simulations of the magnetic reconnection model. Using the scaling law provided by Shibata and Yokoyama (1999, ApJ, 526,…
A hard-to-soft state transition of Aquila X-1 observed with Suzaku
Yamaoka, Kazutaka; Makishima, Kazuo; Nakazawa, Kazuhiro +3 more
The recurrent soft X-ray transient Aquila X-1 was observed with Suzaku for a gross duration of 79.9 ks, on 2011 October 21 when the object was in a rising phase of an outburst. During the observation, the source exhibited a clear spectral transition from the hard state to the soft state, on a time scale of ∼30 ks. Across the transition, the 0.8-10…
The K2-ESPRINT project. VI. K2-105 b, a hot Neptune around a metal-rich G-dwarf
Tamura, Motohide; Hirano, Teruyuki; Sato, Bun'ei +17 more
We report on the confirmation that the candidate transits observed for the star EPIC 211525389 are due to a short-period Neptune-sized planet. The host star, located in K2 campaign field 5, is a metal-rich ([Fe/H] = 0.26 ± 0.05) G-dwarf (Teff = 5430 ± 70 K and log g = 4.48 ± 0.09), based on observations with the High Dispersion Spectrog…
Follow-up observations for the Asteroid Catalog using AKARI Spectroscopic Observations
Hasegawa, Sunao; Usui, Fumihiko; Yanagisawa, Kenshi +1 more
In the 1-2.5 µm range, spectroscopic observations are made on the AcuA-spec asteroids, the spectra of which were obtained in a continuous covered mode between 2.5-5.0 µm by AKARI. Based on the Bus-DeMeo taxonomy (DeMeo et al. 2009, Icarus, 202, 160), all the AcuA-spec asteroids are classified, using both published and our observational…