Search Publications
The AKARI Far-Infrared Surveyor young stellar object catalog
Tamura, Motohide; Kawamura, Akiko; Marton, Gábor +6 more
We demonstrate the use of the AKARI all-sky survey photometric data in the study of galactic star formation. Our aim was to select young stellar objects (YSOs) in the AKARI Far-Infrared Surveyor (FIS) Bright Source Catalogue. We used AKARI/FIS and Wide-field Infrared Survey Explorer (WISE) data to derive mid- and far-infrared colors of YSOs. Class…
Universal profiles of the intracluster medium from Suzaku X-ray and Subaru weak-lensing observations*
Sato, Kosuke; Fukazawa, Yasushi; Nakazawa, Kazuhiro +16 more
We conduct a joint X-ray and weak-lensing study of four relaxed galaxy clusters (Hydra A, A 478, A 1689, and A 1835) observed by both Suzaku and Subaru out to virial radii, with the aim of understanding recently discovered unexpected features of the intracluster medium (ICM) in cluster outskirts. We show that the average hydrostatic-to-lensing tot…
Discovery of recombining plasma in the supernova remnant 3C 391
Takahashi, Tadayuki; Koyama, Katsuji; Nakashima, Shinya +2 more
Recent X-ray study of middle-aged supernova remnants (SNRs) reveals strong radiative recombination continua (RRCs) associated with overionized plasmas, which origin still remains uncertain. We report a discovery of an RRC in the middle-aged SNR 3C 391. If the X-ray spectrum is fitted with a two-temperature plasma model in collisional ionization eq…
Constraining hot plasma in a non-flaring solar active region with FOXSI hard X-ray observations
Krucker, Säm; Shimojo, Masumi; Ishibashi, Kazunori +6 more
We present new constraints on the high-temperature emission measure of a non-flaring solar active region using observations from the recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload. FOXSI has performed the first focused hard X-ray (HXR) observation of the Sun in its first successful flight on 2012 November 2. Focu…
Interpretation of the X-ray spectral variation of 1H 0707-495 with a variable double partial covering model
Ebisawa, Ken; Mizumoto, Misaki; Sameshima, Hiroaki
The narrow-line Seyfert 1 galaxy 1H 0707-495 is known to exhibit significant X-ray spectral variations. Its X-ray energy spectrum is characterized by a strong soft excess emission, an extremely deep iron K-edge structure at ∼ 7 keV, and a putative iron L-line/edge feature at ∼ 1 keV. We have found that the energy spectrum of 1H 0707-495 in 0.5-10 …
Firm detection of a cyclotron resonance feature with Suzaku in the X-ray spectrum of GRO J1008-57 during a giant outburst in 2012
Makishima, Kazuo; Sasano, Makoto; Mihara, Tatehiro +3 more
We report on the firm detection of a cyclotron resonance scattering feature (CRSF) in the X-ray spectrum of the Be X-ray binary pulsar, GRO J1008-57, achieved by the Suzaku Hard X-ray Detector during a giant outburst which was detected by the MAXI Gas Slit Camera in 2012 November. The Suzaku observation was carried out on 2012 November 20, outburs…
Abundances in the ejecta of core-collapse supernova remnants G350.1-0.3 and G349.7+0.2
Koyama, Katsuji; Uchida, Hiroyuki; Yasumi, Masato +5 more
We present Suzaku results of the two Galactic supernova remnants (SNRs) G350.1-0.3 and G349.7+0.2. We find Al and Ni Kα lines from both the SNRs for the first time, in addition to previously detected K-shell lines of Mg, Si, S, Ar, Ca, and Fe. The spectra are well described by two optically thin thermal plasmas: a low-temperature (low-kT) plasma i…
Near-infrared spectroscopy of M dwarfs. I. CO molecule as an abundance indicator of carbon†
Tsuji, Takashi; Nakajima, Tadashi
Based on the near-infrared spectra of 42 M dwarfs, carbon abundances are determined from the ro-vibrational lines of the CO (2-0) band. We apply Teff values based on the angular diameters if available or use the Teff values in a log Teff-M3.4 relation (M3.4 is the absolute magnitude at 3.4 &mi…
A comparative study of infrared asteroid surveys: IRAS, AKARI, and WISE
Hasegawa, Sunao; Usui, Fumihiko; Ootsubo, Takafumi +2 more
We present a comparative study of three infrared asteroid surveys based on the size and albedo data from the Infrared Astronomical Satellite (IRAS), the Japanese infrared satellite AKARI, and the Wide-field Infrared Survey Explorer (WISE). Our study showed that: (i) the total number of asteroids detected with diameter and albedo information with t…
High-speed photospheric material flow observed at the polarity inversion line of a δ-type sunspot producing an X5.4 flare on 2012 March 7
Shimizu, Toshifumi; Lites, Bruce W.; Bamba, Yumi
Solar flares abruptly release the free energy stored as a non-potential magnetic field in the corona and may be accompanied by eruptions of the coronal plasma. Formation of a non-potential magnetic field and the mechanisms for triggering the onset of flares are still poorly understood. In particular, photospheric dynamics observed near those polar…