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18 papers
Observations of DNC and DCO toward the -shaped Filament and Starless Cores in the Orion Molecular Clouds
Ken'ichi Tatematsu, Atsushi Nishimura, Hideo Ogawa +25
Although the deuterium fraction is known to be a powerful evolutionary tracer, its variation within individual molecular cloud cores is still poorly understood. The northern …
First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
The Event Horizon Telescope Collaboration
We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A), the Galactic center source associated with a supermassive black hole. These observati…
The Greenland Telescope: Construction, Commissioning, and Operations in Pituffik
Ming-Tang Chen, Keiichi Asada, Satoki Matsushita +51
In 2018, the Greenland Telescope (GLT) started scientific observation in Greenland. Since then, we have completed several significant improvements and added new capabilities to the…
A ring-like accretion structure in M87 connecting its black hole and jet
Ru-Sen Lu, Keiichi Asada, Thomas P. Krichbaum +118
The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3…
Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Corrugated horn & Optics covering 210-375 GHz band
Yasumasa Yamasaki, Sho Masui, Hideo Ogawa +21
The corrugated horn is a high performance feed often used in radio telescopes. There has been a growing demand for wideband optics and corrugated horns in millimeter and submillime…
Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output
Sho Masui, Yasumasa Yamasaki, Hideo Ogawa +22
We have developed a wideband receiver system for simultaneous observations in CO lines of J = 2-1 and J = 3-2 transitions using the Osaka 1.85-m mm-submm telescope. As a frequency…
Current status and future plan of Osaka Prefecture University 1.85-m mm-submm telescope project
Atsushi Nishimura, Kazuki Tokuda, Ryohei Harada +25
We report the current status of the 1.85-m mm-submm telescope installed at the Nobeyama Radio Observatory (altitude 1400 m) and the future plan. The scientific goal is to reveal th…
Development of the new multi-beam receiver and telescope control system for NASCO
Atsushi Nishimura, Akio Ohama, Kimihiro Kimura +59
We report the current status of the NASCO (NAnten2 Super CO survey as legacy) project which aims to provide all-sky CO data cube of southern hemisphere using the NANTEN2 4-m submil…
High-mass star formation in Orion B triggered by cloud-cloud collision: Merging molecular clouds in NGC 2024
Rei Enokiya, Akio Ohama, Rin Yamada +13
We performed new comprehensive CO(=2--1) observations toward NGC 2024, the most active star forming region in Orion B, with an angular resolution of 100'' obtained…
First M87 Event Horizon Telescope Results. II. Array and Instrumentation
The Event Horizon Telescope Collaboration
The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comp…
A Balloon-Borne Very Long Baseline Interferometry Experiment in the Stratosphere: Systems Design and Developments
Akihiro Doi, Yusuke Kono, Kimihiro Kimura +33
The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has…
Electronics Instrumentation for the Greenland Telescope
Derek Kubo, Chih-Chiang Han, Hiroaki Nishioka +37
The Greenland Telescope project has recently participated in an experiment to image the supermassive black hole shadow at the center of M87 using Very Long Baseline Interferometry…
Detailed CO ( = 1--0, 2--1 and 3--2) observations toward an H{\sc ii} region RCW~32 in the Vela Molecular Ridge
Rei Enokiya, Hidetoshi Sano, Katsuhiro Hayashi +9
We made CO ( = 1--0, 2--1, and 3--2) observations toward an H{\sc ii} region RCW~32 in the Vela Molecular Ridge. The CO gas distribution associated with the H{\sc ii} region was…
A new view of the giant molecular cloud M16 (Eagle Nebula) in 12CO J=1-0 and 2-1 transitions with NANTEN2
Atsushi Nishimura, Jean Costes, Tetsuta Inaba +11
M16, the Eagle Nebula, is an outstanding HII region where extensive high-mass star formation is taking place in the Sagittarius Arm, and hosts the remarkable "pillars" observed wit…
High-mass star formation possibly triggered by cloud-cloud collision in the HII region RCW 34
Katsuhiro Hayashi, Hidetoshi Sano, Rei Enokiya +12
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…
RCW 36 in the Vela Molecular Ridge: Evidence for a high-mass star cluster formation triggered by Cloud-Cloud Collision
Hidetoshi Sano, Rei Enokiya, Katsuhiro Hayashi +21
A collision between two molecular clouds is one possible candidate for high-mass star formation. The HII region RCW 36, located in the Vela molecular ridge, contains a young star c…
Z45: A New 45-GHz Band Dual-Polarization HEMT Receiver for the NRO 45-m Radio Telescope
Fumitaka Nakamura, Hideo Ogawa, Yoshinori Yonekura +20
We developed a dual-linear-polarization HEMT (High Electron Mobility Transistor) amplifier receiver system of the 45-GHz band (hereafter Z45), and installed it in the Nobeyama 45-m…
Cluster Formation Triggered by Filament Collisions in Serpens South
Fumitaka Nakamura, Koji Sugitani, Tomohiro Tanaka +24
The Serpens South infrared dark cloud consists of several filamentary ridges, some of which fragment into dense clumps. On the basis of CCS (), HCN (), N$_2…