Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Atsushi Nishimura is active.

Publication


Featured researches published by Atsushi Nishimura.


The Astrophysical Journal | 2013

Molecular Clumps and Infrared Clusters in the S247, S252, and BFS52 Regions

Tomomi Shimoikura; Kazuhito Dobashi; Hiro Saito; Tomoaki Matsumoto; Fumitaka Nakamura; Atsushi Nishimura; Kimihiro Kimura; Toshikazu Onishi; Hideo Ogawa

We present results of the observations carried out toward the S247, S252, and BFS52 H II regions with various molecular lines using the 1.85?m radio telescope and the 45?m telescope at Nobeyama Radio Observatory. There are at least 11 young infrared clusters (IR clusters) within the observed region. We found that there are two velocity components in 12CO?(J = 2-1), and also that their spatial distributions show an anti-correlation. The IR clusters are located at their interfaces, suggesting that two distinct clouds with different velocities are colliding with each other, which may have induced the cluster formation. Based on 13CO?(J = 1-0) and C18O (J = 1-0) observations, we identified 16 clumps in and around the three H II regions. Eleven of the clumps are associated with the IR clusters and the other five clumps are not associated with any known young stellar objects. We investigated variations in the velocity dispersions of the 16 clumps as a function of the distance from the center of the clusters or the clumps. Clumps with clusters tend to have velocity dispersions that increase with distance from the cluster center, while clumps without clusters show a flat velocity dispersion over the clump extents. A 12CO?outflow has been found in some of the clumps with IR clusters but not in the other clumps, supporting a strong relation of these clumps to the broader velocity dispersion region. We also estimated a mean star formation efficiency of ~30% for the clumps with IR clusters in the three H II regions.


The Astrophysical Journal | 2013

DISCOVERY OF POSSIBLE MOLECULAR COUNTERPARTS TO THE INFRARED DOUBLE HELIX NEBULA IN THE GALACTIC CENTER

Rei Enokiya; Kazufumi Torii; Mathias Schultheis; Yuta Asahina; Ryoji Matsumoto; E. Furuhashi; K. Nakamura; Kazuhito Dobashi; S. Yoshiike; J. Sato; Naoko Furukawa; Nayuta Moribe; Akio Ohama; Hidetoshi Sano; Ryuji Okamoto; Y. Mori; N. Hanaoka; Atsushi Nishimura; Takahiro Hayakawa; Takeshi Okuda; H. Yamamoto; Akiko Kawamura; Norikazu Mizuno; Toshikazu Onishi; Mark R. Morris; Yasuo Fukui

We have discovered two molecular features at radial velocities of ?35?km?s?1 and 0?km?s?1 toward the infrared Double Helix Nebula (DHN) in the Galactic center with NANTEN2. The two features show good spatial correspondence with the DHN. We have also found two elongated molecular ridges at these two velocities distributed vertically to the Galactic plane over 0.?8. The two ridges are linked by broad features in velocity and are likely connected physically with each other. The ratio between the 12CO J = 2-1 and J = 1-0 transitions is 0.8 in the ridges which is larger than the average value 0.5 in the foreground gas, suggesting the two ridges are in the Galactic center. An examination of the K band extinction reveals a good coincidence with the CO 0?km?s?1 ridge and is consistent with a distance of 8 ? 2?kpc. We discuss the possibility that the DHN was created by a magnetic phenomenon incorporating torsional Alfv?n waves launched from the circum-nuclear disk and present a first estimate of the mass and energy involved in the DHN.


Publications of the Astronomical Society of Japan | 2018

High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

Katsuhiro Hayashi; Hidetoshi Sano; Rei Enokiya; Kazufumi Torii; Yusuke Hattori; Mikito Kohno; Shinji Fujita; Atsushi Nishimura; Akio Ohama; H. Yamamoto; Kengo Tachihara; Yutaka Hasegawa; Kimihiro Kimura; Hideo Ogawa; Yasuo Fukui

We report a possibility that the high-mass star located in the HII region RCW 34 was formed by a triggering induced by a collision of molecular clouds. Molecular gas distributions of the


Publications of the Astronomical Society of Japan | 2018

Molecular clouds in the NGC 6334 and NGC 6357 region: Evidence for a 100 pc-scale cloud–cloud collision triggering the Galactic mini-starbursts

Yasuo Fukui; Mikito Kohno; Keiko Yokoyama; Kazufumi Torii; Yusuke Hattori; Hidetoshi Sano; Atsushi Nishimura; Akio Ohama; H. Yamamoto; Kengo Tachihara

^{12}


Publications of the Astronomical Society of Japan | 2018

FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN): Molecular clouds toward W 33; possible evidence for a cloud–cloud collision triggering O star formation

Mikito Kohno; Kazufumi Torii; Kengo Tachihara; Tomofumi Umemoto; Tetsuhiro Minamidani; Atsushi Nishimura; Shinji Fujita; Mitsuhiro Matsuo; Mitsuyoshi Yamagishi; Yuya Tsuda; Mika Kuriki; Nario Kuno; Akio Ohama; Yusuke Hattori; Hidetoshi Sano; H. Yamamoto; Yasuo Fukui

CO and


Publications of the Astronomical Society of Japan | 2018

Molecular clouds toward three Spitzer bubbles S116, S117, and S118: Evidence for a cloud–cloud collision which formed the three H ii regions and a 10 pc scale molecular cavity

Yasuo Fukui; Akio Ohama; Mikito Kohno; Kazufumi Torii; Shinji Fujita; Yusuke Hattori; Atsushi Nishimura; H. Yamamoto; Kengo Tachihara

^{13}


Publications of the Astronomical Society of Japan | 2018

Formation of the young compact cluster GM 24 triggered by a cloud–cloud collision

Yasuo Fukui; Mikito Kohno; Keiko Yokoyama; Atsushi Nishimura; Kazufumi Torii; Yusuke Hattori; Hidetoshi Sano; Akio Ohama; H. Yamamoto; Kengo Tachihara

CO


Publications of the Astronomical Society of Japan | 2018

RCW 36 in the Vela Molecular Ridge: Evidence for high-mass star-cluster formation triggered by cloud–cloud collision

Hidetoshi Sano; Rei Enokiya; Katsuhiro Hayashi; Mitsuyoshi Yamagishi; Shun Saeki; Kazuki Okawa; K. Tsuge; Daichi Tsutsumi; Mikito Kohno; Yusuke Hattori; S. Yoshiike; Shinji Fujita; Atsushi Nishimura; Akio Ohama; Kengo Tachihara; Kazufumi Torii; Yutaka Hasegawa; Kimihiro Kimura; Hideo Ogawa; Graeme F Wong; Catherine Braiding; G. Rowell; Michael G. Burton; Yasuo Fukui

J=


The Astrophysical Journal | 2016

SPATIAL VARIATIONS OF PAH PROPERTIES IN M17SW REVEALED BY SPITZER/IRS SPECTRAL MAPPING

Mitsuyoshi Yamagishi; Hidehiro Kaneda; Daisuke Ishihara; Shinki Oyabu; T. Suzuki; Takashi Onaka; Takumi Nagayama; Tomofumi Umemoto; Tetsuhiro Minamidani; Atsushi Nishimura; Mitsuhiro Matsuo; Shinji Fujita; Yuya Tsuda; Mikito Kohno; Satoshi Ohashi

2-1, and


The Astrophysical Journal | 2018

Discovery of Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Kesteven 79

Mika Kuriki; Hidetoshi Sano; Nario Kuno; Masumichi Seta; Y. Yamane; Tetsuta Inaba; T. Nagaya; S. Yoshiike; Kazuki Okawa; Daichi Tsutsumi; Yusuke Hattori; Mikito Kohno; Shinji Fujita; Atsushi Nishimura; Akio Ohama; Mitsuhiro Matsuo; Yuya Tsuda; K. Torii; Tetsuhiro Minamidani; Tomofumi Umemoto; G. Rowell; Aya Bamba; Kengo Tachihara; Yasuo Fukui

^{12}

Collaboration


Dive into the Atsushi Nishimura's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Kazufumi Torii

Graduate University for Advanced Studies

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge