Search Publications
Spectral analysis of the Galactic supernova remnant Kesteven 69 with Suzaku
Yamauchi, Shigeo; Pannuti, Thomas G.
The results of a Suzaku observation of the supernova remnant (SNR) Kesteven 69 = G21.8-0.6 are presented. To estimate the sky background precisely, we conducted a simultaneous fit of the source region spectrum with the background region spectrum and found that the SNR spectrum is well represented by a two-component ionizing plasma model composed o…
Suzaku spectral analysis of an X-ray emitting plasma in the supernova remnant G352.7-0.1
Nobukawa, Masayoshi; Nobukawa, Kumiko K.; Yamauchi, Shigeo +1 more
The results of a Suzaku observation of the supernova remnant (SNR) G352.7-0.1 are presented in this paper. We conducted spectral analysis based on careful sky background estimation and found an emission line from Al at 1.6 keV, in addition to previously detected emission lines from Mg, Si, S, Ar, Ca, and Fe ions. The X-ray spectrum in the 0.7-10 k…
Spatial structure and dynamical state of the old open cluster Collinder 261 based on a clustering method
Gao, Xinhua
In this paper, we investigate the memberships, spatial structure, and dynamical state of the old open cluster Collinder 261 (8 Gyr) based on Gaia-DR3 data. We develop a robust clustering method to calculate membership probabilities for 24858 sample stars within 20' of the cluster center. We can identify 2619 likely cluster members (including 54 bl…
Suzaku and Chandra study of diffuse X-ray emission from the massive star-forming region RCW 38
Ezoe, Yuichiro; Odaka, Hirokazu; Fukushima, Aoto
In some massive star-forming regions, diffuse X-ray emission has been observed. It can be classified as thermal emission from sub- or several-keV plasmas, non-thermal emission represented by the power law, or a mixture of them. We have studied the nearby (~1.7 kpc) young massive star-forming region RCW 38. In a previous study, non-thermal diffuse …
A close-in planet orbiting giant star HD 167768
Izumiura, Hideyuki; Sato, Bun'ei; Yoshida, Michitoshi +12 more
We report the detection of a giant planet orbiting the G-type giant star HD 167768 from radial velocity measurements using the High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory (OAO). HD 167768 has a mass of $1.08_{-0.12}^{+0.14}\, M_{\odot }$, a radius of $9.70_{-0.25}^{+0.25}\, R_{\odot }$, a metallicity of $[\mbo…
On the influence of shock-cloud interactions on the nonthermal X-ray emission from the supernova remnant RCW 86
Vink, Jacco; Bamba, Aya; Sano, Hidetoshi +1 more
The effect of the surrounding environment of supernova remnant shocks on nonthermal X-rays from accelerated electrons, with or without interacting dense material, is an open issue. We conduct spatially resolved X-ray spectroscopy of the shock-cloud interacting region of RCW 86 with XMM-Newton. It is found that bright soft X-ray filaments surround …
Initial state of the recombining plasma in supernova remnant W 28
Nobukawa, Masayoshi; Nobukawa, Kumiko K.; Yamauchi, Shigeo +2 more
We have investigated supernova remnant (SNR) W 28 using Suzaku archival data, and we report here the results of our spatially resolved analyses. We carried out spectral analyses using a recombining-plasma (RP) model with element-dependent initial ionization temperatures, obtaining ~0.5 keV for Ne, ~0.7 keV for Mg, ~1.0 keV for Si, ~1.2 keV for S, …
12CO and 13CO observation of the low-metallicity dwarf galaxy DDO 154
Komugi, Shinya; Inaba, Miku; Shindou, Tetsuo
The conversion factor from carbon monoxide (CO) intensity to molecular gas mass is a source of large uncertainty in understanding gas and its relation to star formation in galaxies. In particular, the conversion factor in low-metallicity environments have remained elusive, as currently only two galaxies have been detected in any CO isotopes in env…
Photometric and spectroscopic properties of the eclipsing system V864 Monocerotis
Hong, Kyeongsoo; Lee, Jae Woo; Park, Jang-Ho
We present the orbital period variability and evolutionary status of the W UMa-type binary system V864 Mon from accurately measured fundamental parameters. New BV photometric observations of this system were performed in 2019 January and 2022 January, and the first high-resolution spectroscopic observations were carried out on three nights between…
The orbital solution and dynamical masses of the binary system V* PX Virginis
Wang, Xiaoli; Fu, Yanning; Xia, Fang
V* PX Vir is a nearby single-lined spectroscopic binary with the primary being a variable of a BY Dra-type star. It has a period of ~216 d and the components of the system are two low-mass pre-main-sequence stars. By a simultaneous least-squares fit to the radial velocities, the relative positions, and the revised Hipparcos intermediate astrometri…