Search Publications
A comprehensive study of an oscillating eclipsing Algol: Y Camelopardalis
Kahraman Aliçavuş, Filiz; Çelik, Eda
Y Camelopardalis (Y Cam) is classified as one of the oscillating eclipsing Algol (oEA) systems, which feature a $\delta$ Scuti-type pulsating component alongside mass transfer phenomena. oEA systems are invaluable for probing the evolutionary processes and internal structures of binary components, offering insights through their binary variations …
KAgoshima Galactic Object survey with Nobeyama 45 m telescope by Mapping in Ammonia lines (KAGONMA): Discovery of parsec-scale CO depletion in the Canis Major star-forming region
Shimajiri, Yoshito; Sunada, Kazuyoshi; Omodaka, Toshihiro +6 more
In observational studies of infrared dark clouds, the number of detections of CO freeze-out on to dust grains (CO depletion) at the pc scale is extremely limited, and the conditions for its occurrence are, therefore, still unknown. We report a new object where pc-scale CO depletion is expected. As part of the Kagoshima Galactic Object survey with …
Suzaku observation of an iron K-shell line in the spiral galaxy NGC 6946
Yamauchi, Shigeo; Inaba, Azusa; Anraku, Yumiko
An emission line at ~6.7 keV is attributable to an He-like iron K-shell transition, which indicates existence of a thin thermal plasma with a temperature of several keV. Using Suzaku archival data, we searched for the iron K-line from the spiral galaxy NGC 6946, and found it at 6.68 ± 0.07 keV at the 3.1σ level in the central $r\le {2.^{\prime }5}…
Near-ultraviolet radiation toward molecular cloud N4 in W 50/SS 433: Evidence for direct interaction of the jet with molecular cloud
Takeuchi, Tsutomu T.; Yamamoto, Hiroaki; Ishikawa, Tatsumi
We compared the molecular clouds in the western part of SS 433 with near-ultraviolet radiation data obtained from GALEX. Near-ultraviolet radiation is prominently confirmed toward only N4, while no near-ultraviolet radiation is detected toward N1, N2, or N3. The radiative region of near-ultraviolet radiation is nearly the same as the CO-emitting r…
Discovery of diffuse radio source in Abell 1060
Nakazawa, Kazuhiro; Akahori, Takuya; Kurahara, Kohei +2 more
Non-thermal components in the intra-cluster medium (ICM), such as turbulence, magnetic field, and cosmic rays, imprint the past and current energetic activities of jets from active galactic nuclei (AGN) of member galaxies as well as disturbance caused by galaxy cluster mergers. Meter- and centimeter-radio observations of synchrotron radiation allo…
MK-like spectral classification for hot subdwarf stars with LAMOST spectra
Lei, Zhenxin; Zou, Xuan
An MK-like spectral classification has been conducted for 1224 hot subdwarf stars with LAMOST DR9 low-resolution spectra. The whole sample was divided into four categories according to the spectral line characteristics: He-normal, He-weak, He-strong C, and He-strong. Each selected spectrum was assigned a spectral class, a luminosity class, and a h…
Plasma diagnostics of supernova remnant 3C 400.2 by Suzaku observations
Nobukawa, Masayoshi; Uchiyama, Hideki; Nobukawa, Kumiko K. +2 more
We report on the results of plasma diagnostics of the supernova remnant (SNR) 3C 400.2, which has been reported to have a recombining plasma by previous studies. For careful background estimation, we simultaneously fitted spectra extracted from the SNR and background regions and evaluated the SNR emission contaminating the background-region spectr…
Low abundances of TiO and VO on the dayside of KELT-9 b: Insights from ground-based photometric observations
Ikuta, Kai; Fukui, Akihiko; Narita, Norio +21 more
We present ground-based photometric observations of secondary eclipses of the hottest known planet KELT-9 b using MuSCAT2 and Sinistro. We detect secondary eclipse signals in i and
Dark matter search in the Perseus cluster with simultaneous analysis of Hitomi and Suzaku data
Kitamoto, Shunji; Sawada, Makoto; Tamura, Takayuki +1 more
The reported detection of a 3.5 keV emission line in the Perseus cluster, possibly originating from dark matter decay, is still under scrutiny. Despite extensive observations, the detection has not yet been confirmed, and its origin remains a topic of active debate. Most of the previous searches relied on spectroscopy with X-ray charge-coupled dev…
The mass of TOI-519 b: A close-in giant planet transiting a metal-rich mid-M dwarf
Ikuta, Kai; Tamura, Motohide; Hirano, Teruyuki +33 more
We report on the determination of the mass of TOI-519 b, a transiting substellar object around a mid-M dwarf. We carried out radial velocity measurements using Subaru/InfraRed Doppler (IRD), revealing that TOI-519 b is a planet with a mass of $0.463^{+0.082}_{-0.088}\, M_{\rm Jup}$. We also found that the host star is metal rich ([Fe/H] = 0.27 ± 0…