Search Publications
Red dwarf contact binary V0627 Hydrae
Zhu, Li-Ying; Liu, Liang; Xu, Hu-Shan +2 more
New complete light curves in B, V, RC, and IC bands for the short-period eclipsing binary V0627 Hya (period shorter than 0.22 d) are presented. From the longer wavelength to the shorter one, the amplitudes of the light variation become larger. The different height of the successive maxima in each band's light curve could be s…
Do blue galaxy-clusters have hot intracluster gas?
Oguri, Masamune; Kodama, Tadayuki; Okabe, Nobuhiro +5 more
We present herein a systematic X-ray analysis of blue galaxy clusters at z = 0.84 discovered by the Subaru telescope. The sample consisted of 43 clusters identified by combining red-sequence and blue-cloud surveys, covering a wide range of emitter fractions (i.e., 0.3-0.8). The spatial extent of the over-density region of emitter galaxies was appr…
A trio of giant planets orbiting evolved star HD 184010
Izumiura, Hideyuki; Sato, Bun'ei; Yoshida, Michitoshi +11 more
We report the discovery of a triple-giant-planet system around an evolved star HD 184010 (HR 7421, HIP 96016). This discovery is based on observations from Okayama Planet Search Program, a precise radial velocity survey, undertaken at Okayama Astrophysical Observatory between 2004 April and 2021 June. The star is K0 type and located at the beginni…
Discovery of a new supergiant fast X-ray transient MAXI J0709-159 associated with the Be star LY Canis Majoris
Liu, Zhu; Kawai, Nobuyuki; Shidatsu, Megumi +10 more
We report on the discovery of a new supergiant fast X-ray transient (SFXT), MAXI J0709-159, and its identification with LY CMa (also known as HD 54786). On 2022 January 25, a new flaring X-ray object, named MAXI J0709-159, was detected by the Monitor of All-sky X-ray Image (MAXI). Two flaring activities were observed in two scans ~3 hr apart, wher…
X-ray hot spots in the eastern ear of the supernova remnant W 50 and the microquasar SS 433 system
Katsuda, Satoru; Sato, Toshiki; Uchiyama, Hideki +10 more
We examined the X-ray and radio spatial structure at the eastern ear of the W 50/SS 433 system to clarify a characteristic feature of the termination region of the SS 433 jet, and found that a hot spot ahead of the filament structure, which is considered to be a terminal shock of the SS 433 eastern jet, is clearly different from a single point sou…
Cloud-cloud collisions and triggered star formation
Inoue, Tsuyoshi; Tachihara, Kengo; Fukui, Yasuo +2 more
Star formation is a fundamental process for galactic evolution. One issue over the last several decades has been determining whether star formation is induced by external triggers or self-regulated in a closed system. The role of an external trigger, which can effectively collect mass in a small volume, has attracted particular attention in connec…
Time-resolved spectroscopy and photometry of M dwarf flare star YZ Canis Minoris with OISTER and TESS: Blue asymmetry in the Hα line during the non-white light flare
Notsu, Yuta; Kowalski, Adam F.; Maehara, Hiroyuki +15 more
In this paper, we present the results from spectroscopic and photometric observations of the M-type flare star YZ CMi in the framework of the Optical and Infrared Synergetic Telescopes for Education and Research (OISTER) collaborations during the Transiting Exoplanet Survey Satellite (TESS) observation period. We detected 145 white-light flares fr…
CO Multi-line Imaging of Nearby Galaxies (COMING). IX. 12CO(J = 2-1)/12CO(J = 1-0) line ratio on kiloparsec scales
Kobayashi, Masato I. N.; Kuno, Nario; Miyamoto, Yusuke +8 more
While molecular gas mass is usually derived from 12CO(J = 1-0)—the most fundamental line for exploring molecular gas—it is often derived from 12CO(J = 2-1) assuming a constant 12CO(J = 2-1) $/$ 12CO(J = 1-0) line ratio (R2/1). We present variations of R2/1 and effects of the assumpt…
ALMA CO observations of a giant molecular cloud in M 33: Evidence for high-mass star formation triggered by cloud-cloud collisions
Tokuda, Kazuki; Tachihara, Kengo; Sasaki, Manami +14 more
We report the first evidence for high-mass star formation triggered by collisions of molecular clouds in M 33. Using the Atacama Large Millimeter/submillimeter Array, we spatially resolved filamentary structures of giant molecular cloud 37 in M 33 using 12CO(J = 2-1), 13CO(J = 2-1), and C18O(J = 2-1) line emission …
The formation of young massive clusters triggered by cloud-cloud collisions in the Antennae galaxies NGC 4038/NGC 4039
Tokuda, Kazuki; Tachihara, Kengo; Ueda, Junko +5 more
The formation mechanism of super star clusters (SSCs), present-day analogs of the ancient globulars, still remains elusive. The major merger that is the Antennae galaxies is forming SSCs and is one of the primary targets to test the cluster formation mechanism. We reanalyzed the archival ALMA CO data of the Antennae and found three typical observa…