Search Publications
Suzaku detection of solar wind charge exchange emission from a variety of highly ionized ions in an interplanetary coronal mass ejection
Katsuda, Satoru; Ezoe, Yuichiro; Yoneyama, Tomokage +8 more
X-ray emission generated through solar-wind charge exchange (SWCX) is known to contaminate X-ray observation data, the amount of which is often significant or even dominant, particularly in the soft X-ray band, when the main target consists of comparatively weak diffuse sources, depending on the space weather during the observation. In particular,…
Spatial distribution of the X-ray-emitting plasma of U Geminorum in quiescence and outburst
Maeda, Yoshitomo; Ishida, Manabu; Hayashi, Takayuki +2 more
We present our analysis of the Suzaku data of U Geminorum (U Gem) from 2012 both in quiescence and outburst. Unlike SS Cygni (SS Cyg), the hard X-ray flux of U Gem is known to increase at times of optical outburst. A sophisticated spectral model and reliable distance estimate now reveal that this can be attributed to the fact that the mass accreti…
The nature of bright C-complex asteroids
Hasegawa, Sunao; Usui, Fumihiko; Kuroda, Daisuke +1 more
Most C-complex asteroids have albedo values less than 0.1, but there are some high-albedo (bright) C-complex asteroids with albedo values exceeding 0.1. To reveal the nature and origin of bright C-complex asteroids, we conducted spectroscopic observations of the asteroids at visible and near-infrared wavelengths. As a result, the bright B-, C-, an…
Photometric follow-up observations and transit timing analysis of HAT-P-37b
Li, Kai; Liu, Yuan; Yang, Jia-Mei +1 more
We performed follow-up photometric observations on exoplanetary system HAT-P-37 from 2011 February to 2019 September. The nine new transit light curves of the R and V bands are presented in this work. Based on the new light curves and published literature data, the physical and orbital parameters of HAT-P-37 are refined. In addition, mid-transit t…
FUGIN hot core survey. I. Survey method and initial results for l = 10°-20°
Hasegawa, Tetsuo; Saito, Hiro; Seta, Masumichi +4 more
We have developed a method to make a spectral-line-based survey of hot cores, which represent an important stage of high-mass star formation, and applied the method to the data of the FUGIN (FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope) survey. First, we select hot core candidates by searching the FUGIN data for t…
A three-dimensional velocity of an erupting prominence prior to a coronal mass ejection
Shibata, Kazunari; Ishii, Takako T.; Kitai, Reizaburo +10 more
We present a detailed three-dimensional (3D) view of a prominence eruption, coronal loop expansion, and coronal mass ejections (CMEs) associated with an M4.4 flare that occurred on 2011 March 8 in the active region NOAA 11165. Full-disk Hα images of the flare and filament ejection were successfully obtained by the Flare Monitoring Telescope (FMT) …
Studies of emission regions of the X-ray pulsar Hercules X-1 with pulse-phase-resolved spectra observed with Suzaku
Dotani, Tadayasu; Inoue, Hajime; Kondo, Keisuke
Pulse-phase-resolved X-ray spectra of the X-ray pulsar Her X-1 observed with Suzaku are analyzed. The analysis is based on a hypothesis that the observed variations of the continuum spectra associated with the neutron star spin originate in the changes of the projection areas of the emission regions viewed from the observer, and that the spectral …
Suzaku observations of Jovian diffuse hard X-ray emission
Miyoshi, Yoshizumi; Ezoe, Yuichiro; Ishikawa, Kumi +6 more
We report on results of systematic analyses of the entire three X-ray data sets of Jupiter taken by Suzaku in 2006, 2012, and 2014. Jovian diffuse hard X-ray emission was discovered by Suzaku in 2006 when the solar activity went toward its minimum. The diffuse emission was spatially consistent with the Jovian inner magnetosphere and was spectrally…
Dust dissipation timescales in the intermediate and outer regions of protoplanetary disks
Nakagawa, Takao; Kwon, Jungmi; Takita, Satoshi +2 more
Dust and gas in protoplanetary disks dissipate as central stars evolve. In order to estimate the dust dissipation timescales in the protoplanetary disks, we stacked the WISE 12 and 22, and the AKARI 90 µm survey images of known T Tauri stars and derived the average fluxes, well below the survey flux limit in the 90 µm band. We classifi…
Searching for periodic variations in radial velocities after the removal of orbital motions of spectroscopic binaries
Sato, Bun'ei; Itoh, Yoichi; Katoh, Noriyuki
This study focuses on periodic variations of radial velocities (RVs) after removing the orbital motion of 33 spectroscopic binaries. The RVs were monitored from 2003 to 2012 and published in Katoh et al. (2013, AJ, 145, 41). Their RV precision was determined to be ∼10 m s-1 utilizing an I2 cell. We investigated the periodic v…