Search Publications
CO observations toward the isolated mid-infrared bubble S44: External triggering of O-star formation by a cloud-cloud collision
Tachihara, Kengo; Fukui, Yasuo; Sano, Hidetoshi +11 more
We have performed a multi-wavelength study of the mid-infrared bubble S44 to investigate the origin of isolated high-mass star(s) and the star-formation process around the bubble formed by the H II region. We report on the results of new CO observations (12CO, 13CO J = 1-0, and 12CO J = 3-2) toward the isolated bub…
Detailed analysis of the poorly studied northern open cluster NGC 1348 using multi-color photometry and GAIA EDR3 astrometry
Rangwal, Geeta; Zhu, Qingfeng; Jiang, Ing-Guey +5 more
The membership determination for open clusters in noisy environments of the Milky Way is still an open problem. In this paper, our main aim is to provide the membership probability of stars using proper motions and parallax values of stars using Gaia Third Data Release astrometry. Apart from the Gaia astrometry, we have also used other photometric…
On the nature of the anomalous event in 2021 in the dwarf nova SS Cygni and its multi-wavelength transition
Maehara, Hiroyuki; Enoto, Teruaki; Shidatsu, Megumi +20 more
SS Cyg has long been recognized as the prototype of a group of dwarf novae that show only outbursts. However, this object has entered a quite anomalous event in 2021, which at first appeared to be standstill, i.e., an almost constant luminosity state observed in Z Cam-type dwarf novae. This unexpected event gives us a great opportunity to reconsid…
KIC 9406652: A laboratory for tilted disks in cataclysmic variable stars. II. Modeling of the orbital light curves
Kimura, Mariko; Osaki, Yoji
KIC 9406652, one of the recently identified IW And-type dwarf novae, is the best target for studying the tilted disk in cataclysmic variable stars. In a previous paper by Kimura et al. (2020b, PASJ, 72, 94), we analyzed its Kepler light curves and found that its orbital light curves during the brightening stage were dominated by the reflection eff…
Spectroscopic and photometric observations of dwarf nova superoutbursts by the 3.8 m telescope Seimei and the Variable Star Network
Ruiz, Javier; Maehara, Hiroyuki; Namekata, Kosuke +58 more
We present spectroscopic and photometric observations of 17 dwarf-nova superoutbursts obtained by KOOLS-IFU mounted on the 3.8 m telescope Seimei at the Okayama Observatory of Kyoto University and through the Variable Star Network collaboration (VSNET). Our spectroscopic observations for six outbursts were performed within 1 d of their optical pea…
Characterization of M dwarfs using optical mid-resolution spectra for exploration of small exoplanets
Wisniewski, John; Hirano, Teruyuki; Sato, Bun'ei +4 more
We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (Teff), and radii. Our spectra were obtained using several optical spectrometers with spectral resolutions that range from 1200 to 10000. As many as 97% of the observed M-type dwarfs have a spectral type of M3-M6, with a typic…
Subaru Hyper Suprime-Cam revisits the large-scale environmental dependence on galaxy morphology over 360 deg2 at z = 0.3-0.6
Shimakawa, Rhythm; Tanaka, Masayuki; Tanaka, Takumi S. +1 more
This study investigates the role of large-scale environments on the fraction of spiral galaxies at z = 0.3-0.6 sliced to three redshift bins of Δz = 0.1. Here, we sample 276220 massive galaxies in a limited stellar mass of 5 × 1010 solar mass (~M*) over 360 deg2, as obtained from the Second Public Data Release of the Hyper Su…
Fundamental parameters for 30 faint open clusters with Gaia EDR3 based on the more reliable members
Ding, Xu; Yu, Xiao-Guang; Ji, Kai-Fan +4 more
An open cluster is an ideal region to study the evolution of stars. In this work, we use Gaia Early Data Release 3 (Gaia EDR3) to derive the fundamental parameters of 30 faint open clusters listed in the catalogue given by Cantat-Gaudin et al. (2018, A&A, 618, A93), but the G magnitude of all of the member stars of that catalogue is brighter t…
Cloud structures in M 17 SWex : Possible cloud-cloud collision
Sanhueza, Patricio; Kim, Kee-Tae; Nakamura, Fumitaka +11 more
Using wide-field 13CO (J = 1-0) data taken with the Nobeyama 45 m telescope, we investigate cloud structures of the infrared dark cloud complex in M 17 with Spectral Clustering for Interstellar Molecular Emission Segmentation. In total, we identified 118 clouds that include 11 large clouds with radii larger than 1 pc. The clouds are mai…
Energy estimation of high-energy particles associated with the SS 433/W 50 system through radio observation at 1.4 GHz
Sakemi, Haruka; Ohmura, Takumi; Machida, Mami +1 more
The radio nebula W 50 is a unique object interacting with the jets of the microquasar SS 433. The SS 433/W 50 system is a good target for investigating the energy of cosmic-ray particles accelerated by galactic jets. We report observations of the radio nebula W 50 conducted with the National Science Foundation's Karl G. Jansky Very Large Array in …