Search Publications
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…
O I fluorescent line contamination in soft X-ray diffuse background obtained with Suzaku/XIS
Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Takei, Yoh +1 more
The quantitative measurement of O VII line intensity is a powerful method for understanding the soft X-ray diffuse background. By systematically analyzing the O VII line intensity in 145 high-latitude Suzaku/XIS observations, the flux of O I fluorescent line in the XIS spectrum, contaminating the O VII l…
Coronal behavior before the large flare onset
Kusano, Kanya; Bamba, Yumi; Imada, Shinsuke
Flares are a major explosive event in our solar system. They are often followed by a coronal mass ejection that has the potential to trigger geomagnetic storms. There are various studies aiming to predict when and where the flares are likely to occur. Most of these studies mainly discuss the photospheric and chromospheric activity before the flare…
Temperature and entropy profiles to the virial radius of the Abell 1246 cluster observed with Suzaku
Sato, Kosuke; Ohashi, Takaya; Yamasaki, Noriko Y. +2 more
We report properties of the intracluster medium (ICM) in Abell 1246 to the virial radius (r200) and further outside as observed with Suzaku. The ICM emission is clearly detected to r200, and we derive profiles of electron temperature, density, entropy, and cluster mass based on the spectral analysis. The temperature shows var…
Suzaku view of the neutron star in the dipping source 4U 1822-37
Enoto, Teruaki; Makishima, Kazuo; Zhang, Zhongli +2 more
The dipping X-ray source 4U 1822-37 was observed by Suzaku on 2006 October 20 for a net exposure of 37 ks. The source was detected with the XIS at a 1-10 keV flux of 5.5 × 10-10 erg cm-2 s-1, and with the HXD (HXD-PIN) at a 10-50 keV flux of 8.9 × 10-10 erg cm-2 s-1. With HXD-PIN, t…
Structual study of Galactic hot gas toward Markarian 421 from X-ray absorption and emission lines
Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Wang, Q. Daniel +4 more
We present a structural study of the hot ISM in the Galactic halo along the sight line toward the bright active galactic nucleus Mkn 421. The O VII and O VIII absorption lines were measured with the Low Energy Transmission Grating Spectrograph aboard Chandra toward Mkn 421; the O VII and O VIII emission lines were observed in the adjacent fields o…
Coronal loops above an active region: Observation versus model
Peter, Hardi; Bingert, Sven; Bourdin, Philippe-A.
We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling laws for coronal loop properties like the temperature and density. Our 3D MHD model is driven from below by Hino…
X-ray spectroscopy of the mixed morphology supernova remnant W 28 with XMM-Newton
Ishida, Manabu; Bamba, Aya; Tatematsu, Ken'ichi +6 more
We report on spatially resolved X-ray spectroscopy of the north-eastern part of the mixed morphology supernova remnant (SNR) W 28 with XMM-Newton. The observed field of view includes a prominent and twisted shell emission forming the edge of this SNR as well as part of the center-filled X-ray emission brightening toward the south-west edge of the …