Star Formation in Relic HII Regions of the First Stars: Binarity and Outflow Driving (2009)
Machida, Masahiro N., Omukai, Kazuyuki, Matsumoto, Tomoaki
Star formation in relic HII regions of the first stars is investigated using magneto-hydrodynamical simulations with a nested grid method that covers 10 orders of magnitude in spatial scale and 20...
First Direct Simulation of Brown Dwarf Formation in a Compact Cloud Core (2009)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
Brown dwarf formation and star formation efficiency are studied using a nested grid simulation that covers five orders of magnitude in spatial scale (10^4 - 0.1AU). Starting with a rotating...
Binary Formation with Different Metallicities: Dependence on Initial Conditions (2009)
Machida, Masahiro N., Omukai, Kazuyuki, Matsumoto, Tomoaki, Inutsuka, Shu-ichiro
The fragmentation process in collapsing clouds with various metallicities is studied using three-dimensional nested-grid hydrodynamics. Initial clouds are specified by three parameters: cloud...
The Circumbinary Outflow: A Protostellar Outflow Driven by a Circumbinary Disk (2009)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
The protostellar outflows have indispensable role in the formation of single stars, because they carry off the excess angular momentum from the centre of the shrinking gas cloud, and permits further...
Protostellar Jet and Outflow in the Collapsing Cloud Core (2009)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
We investigate the driving mechanism of outflows and jets in star formation process using resistive MHD nested grid simulations. We found two distinct flows in the collapsing cloud core: Low-velocity...
Three Dimensional Magnetohydrodynamical Simulations of Core Collapse Supernova (2008)
Mikami, Hayato, Sato, Yuji, Matsumoto, Tomoaki, Hanawa, Tomoyuki
We show three-dimensional magnetohydrodynamical simulations of core collapse supernova in which the progenitor has magnetic fields inclined to the rotation axis. The simulations employed a simple...
Magneto-Hydrodynamics of Population III Star Formation (2008)
Machida, Masahiro N., Matsumoto, Tomoaki, Inutsuka, Shu-ichiro
Jet driving and fragmentation process in collapsing primordial cloud are studied using three-dimensional MHD nested grid simulations. Starting from a rotating magnetized spherical cloud with the...
Angular Momentum Accretion onto a Gas Giant Planet (2008)
Machida, Masahiro N., Kokubo, Eiichiro, Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
We investigate the accretion of angular momentum onto a protoplanet system using three-dimensional hydrodynamical simulations. We consider a local region around a protoplanet in a protoplanetary disk...
Fumitaka Nakamura Faculty, Fumitaka Nakamura, Tomoyuki Hanawa, Tomoaki Matsumoto
We followed fragmentation of magnetized filamentary clouds and formation of disks with two-dimensional numerical simulations. A filamentary cloud with longitudinal magnetic fields fragments to form...
Fumitaka Nakamura Faculty, Fumitaka Nakamura, Tomoyuki Hanawa, Tomoaki Matsumoto
We followed fragmentation of magnetized filamentary clouds and formation of disks with two-dimensional numerical simulations. A filamentary cloud with longitudinal magnetic fields fragments to form...
Fumitakanakamura Faculty Of, Tomoyuki Hanawa, Tomoaki Matsumoto
Wefollowed fragmentation of magnetized filamentary clouds and formation of disks with two-dimensional numerical simulations. A filamentary cloud with longitudinal magnetic fields fragments to form...
Gravitational Collapse of a Rotating Cloud to Form Star and Disk System (2007)
Tomoyuki Hanawa, Tomoaki Matsumoto
Wepresenttwo-dimensional numerical simulations of gravitational collapse of a rotating cloud. The collaping cloud forms a dynamically contracting disk. The disk structure can be well reproduced by a...
Gravitational Collapse of a Rotating Cloud to Form Star and Disk System (2007)
Tomoyuki Hanawa, Tomoaki Matsumoto, Fumitaka Nakamura
We present two-dimensional numerical simulations of gravitational collapse of a rotating cloud. The collaping cloud forms a dynamically contracting disk. The disk structure can be well reproduced by...
Conditions for the Formation of First-Star Binaries (2007)
Machida, Masahiro N., Omukai, Kazuyuki, Matsumoto, Tomoaki, Inutsuka, Shu-ichiro
The fragmentation process of primordial-gas cores during prestellar collapse is studied using three-dimensional nested-grid hydrodynamics. Starting from the initial central number density of n...
Formation Scenario for Wide and Close Binary Systems (2007)
Machida, Masahiro N., Tomisaka, Kohji, Matsumoto, Tomoaki, Inutsuka, Shu-ichiro
Fragmentation and binary formation processes are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic...
Driving Mechanism of Jets and Outflows in Star Formation Process (2007)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
The driving mechanism of jets and outflows in star formation process is studied using resistive MHD nested grid simulations. We calculated cloud evolution from the molecular cloud core to the stellar...
Magnetic Fields and Rotations of Protostars (2007)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
The evolution of the magnetic field and angular momentum in the collapsing cloud core is studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal...
Near-Infrared Imaging Polarimetry of the NGC 2071 Star Forming Region with SIRPOL (2007)
Tamura, Motohide, Kandori, Ryo, Hashimoto, Jun, Kusakabe, Nobuhiko, Nakajima, Yasushi, Ssato, Shuji, ...
We have conducted deep JHKs imaging polarimetry of a ~8' x 8' area of the NGC 2071 star forming region. Our polarization data have revealed various infrared reflection nebulae (IRNe) associated with...
A new numerical code, called SFUMATO, for solving self-gravitational magnetohydrodynamics (MHD) problems using adaptive mesh refinement (AMR) is presented. A block-structured grid is adopted as the...
Kohji Tomisaka, Masahiro N. Machida, Tomoaki Matsumoto, Kazuya Saigo
Numerical Simulations of Collapse and Fragmentation of Magnetized Molecular Cloud Cores -- Formation of Binary
The First Jet in the Universe: Protostellar Jets from the First Stars (2006)
Machida, Masahiro N., Omukai, Kazuyuki, Matsumoto, Tomoaki, Inutsuka, Shu-ichiro
The protostellar jets driven by the formation of the first stars are studied by using MHD nested grid simulations. Starting from a slowly rotating spherical cloud of 5.1 times 10^4 Msun permeated by...
Outflows driven by Giant Protoplanets (2006)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
We investigate outflows driven by a giant protoplanet using three-dimensional MHD nested grid simulations. We consider a local region around the protoplanet in the protoplanetary disk, and calculate...
Second Core Formation and High Speed Jets: Resistive MHD Nested Grid Simulations (2006)
Machida, Masahiro N., Inutsuka, Shu-ichiro, Matsumoto, Tomoaki
The stellar core formation and high speed jets driven by the formed core are studied by using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud...
Evolution of Rotating Molecular Cloud Core with Oblique Magnetic Field (2006)
Machida, Masahiro N., Matsumoto, Tomoaki, Hanawa, Tomoyuki, Tomisaka, Kohji
We studied the collapse of rotating molecular cloud cores with inclined magnetic fields, based on three-dimensional numerical simulations.The numerical simulations start from a rotating Bonnor-Ebert...
Alignment of Outflows with Magnetic Fields in Cloud Cores (2005)
Matsumoto, Tomoaki, Nakazato, Takeshi, Tomisaka, Kohji
We estimate the polarized thermal dust emission from MHD simulations of protostellar collapse and outflow formation in order to investigate alignment of outflows with magnetic fields. The...
Collapse and Fragmentation of Rotating Magnetized Clouds. I. Magnetic Flux - Spin Relation (2005)
Machida, Masahiro N, Matsumoto, Tomoaki, Tomisaka, Kohji, Hanawa, Tomoyuki
We discuss evolution of the magnetic flux density and angular velocity in a molecular cloud core, on the basis of three-dimensional numerical simulations, in which a rotating magnetized cloud...
Machida, Masahiro N, Matsumoto, Tomoaki, Hanawa, Tomoyuki, Tomisaka, Kohji
Subsequent to Paper I, the evolution and fragmentation of a rotating magnetized cloud are studied with use of three-dimensional MHD nested-grid simulations. After the isothermal runaway collapse, an...
Fujita, Yutaka, Matsumoto, Tomoaki, Wada, Keiichi, Furusho, Tae
This is the first attempt to construct detailed X-ray spectra of clusters of galaxies from the results of high-resolution hydrodynamic simulations and simulate X-ray observations in order to study...
The Formation of Population III Binaries (2004)
Saigo, Kazuya, Matsumoto, Tomoaki, Umemura, Masayuki
We explore the possibility for the formation of Population III binaries. The collapse of a rotating cylinder is simulated with a three-dimensional, high-resolution nested grid, assuming the thermal...
Fujita, Yutaka, Matsumoto, Tomoaki, Wada, Keiichi
Based on high-resolution two-dimensional hydrodynamic simulations, we show that the bulk gas motions in a cluster of galaxies, which are naturally expected during the process of hierarchical...
First MHD Simulation of Collapse and Fragmentation of Magnetized Molecular Cloud Cores (2003)
Machida, Masahiro N, Tomisaka, Kohji, Matsumoto, Tomoaki
This is the first paper about the fragmentation and mass outflow in the molecular cloud by using three-dimensional MHD nested-grid simulations. The binary star formation process is studied paying...
Matsumoto, Tomoaki, Hanawa, Tomoyuki
The fragmentation of molecular cloud cores a factor of 1.1 denser than the critical Bonnor-Ebert sphere is examined though three-dimensional numerical simulations. A nested grid is employed to...
A Fast Algorithm for Solving the Poisson Equation on a Nested Grid (2002)
Matsumoto, Tomoaki, Hanawa, Tomoyuki
We present a numerical method for solving the Poisson equation on a nested grid. The nested grid consists of uniform grids having different grid spacing and is designed to cover the space closer to...
Stability of Toomre-Hayashi Disk (2000)
Hanawa, Tomoyuki, Saigo, Kazuya, Matsumoto, Tomoaki
We investigate stability of Toomre-Hayashi model for a self-gravitating, rotating gas disk. The rotation velocity, $ v_\phi $, and sound speed, $ c _{\rm s} $, are spatially constant in the model. We...
Growth of a Vortex Mode during Gravitational Collapse Resulting in Type II Supernova (2000)
Hanawa, Tomoyuki, Matsumoto, Tomoaki
We investigate stability of a gravitationally collapsing iron core against non-spherical perturbation. The gravitationally collapsing iron core is approximated by a similarity solution for...
Stability of Dynamically Collapsing Gas Sphere (1999)
Hanawa, Tomoyuki, Matsumoto, Tomoaki
We discuss stability of dynamically collapsing gas spheres. We use a similarity solution for a dynamically collapsing sphere as the unperturbed state. In the similarity solution the gas pressure is...
Fragmentation of a Magnetized Filamentary Molecular Cloud Rotating around its Axis (1994)
Matsumoto, Tomoaki, Nakamura, Fumitaka, Hanawa, Tomoyuki
The dynamical instability of a self-gravitating magnetized filamentary cloud was investigated while taking account of rotation around its axis. The filamentary cloud of our model is supported against...