| Masahiro N Machida | Last modified date：2024.04.05 |
Professor /
Material Science of Solar Planets /
Department of Earth and Planetary Sciences /
Faculty of Sciences
Presentations
| 1. | Takayuki Kotani, Motohide Tamura, Jun Nishikawa, Akitoshi Ueda, Masayuki Kuzuhara, Masashi Omiya, Jun Hashimoto, Masato Ishizuka, Teruyuki Hirano, Hiroshi Suto, Takashi Kurokawa, Tsukasa Kokubo, Takahiro Mori, Yosuke Tanaka, Ken Kashiwagi, Mihoko Konishi, Tomoyuki Kudo, Bun'Ei Sato, Shane Jacobson, Klaus W. Hodapp, Donald B. Hall, Wako Aoki, Tomonori Usuda, Shogo Nishiyama, Tadashi Nakajima, Yuji Ikeda, Tomoyasu Yamamuro, Jun Ichi Morino, Haruka Baba, Ko Hosokawa, Hiroyuki Ishikawa, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Nobuhiko Kusakabe, Jungmi Kwon, Masahiro Ikoma, Yasunori Hori, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Hajime Kawahara, Guyon Olivier, Nemanja Jovanovic, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Hiroshi Terada, Daehyeon Oh, The infrared Doppler (IRD) instrument for the Subaru telescope Instrument description and commissioning results, Ground-based and Airborne Instrumentation for Astronomy VII 2018, 2018.01, The Infrared Doppler (IRD) instrument is a fiber-fed high-resolution NIR spectrometer for the Subaru telescope covering the Y,J,H-bands simultaneously with a maximum spectral resolution of 70,000. The main purpose of IRD is a search for Earth-mass planets around nearby M-dwarfs by precise radial velocity measurements, as well as a spectroscopic characterization of exoplanet atmospheres. We report the current status of the instrument, which is undergoing commissioning at the Subaru Telescope, and the first light observation successfully done in August 2017. The general description of the instrument will be given including spectrometer optics, fiber injection system, cryogenic system, scrambler, and laser frequency comb. A large strategic survey mainly focused on late-type M-dwarfs is planned to start from 2019.. |
| 2. | K. Tomida, Masahiro Machida, T. Hosokawa, Y. Sakurai, C. H. Lin, Grand design spiral arms in a young forming circumstellar disk, 2017 Conference Francesco's Legacy: Star Formation in Space and Time, 2017.01, We study formation and long-term evolution of a circumstellar disk using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum. Although the spiral arms disappear in a few rotations, new spiral arms form recurrently throughout the Class-0 and I phases as the disk soon becomes unstable again by gas accretion. Using synthetic observation, we compare our model with a recent high-resolution observation of Elias 2-27, whose circumstellar disk has grand design spiral arms, and find good agreement. Our model suggests that the grand design spiral arms around Elias 2-27 are consistent with material arms formed by gravitational instability. If such spiral arms commonly exist in young circumstellar disks, it implies that young circumstellar disks are considerably massive and gravitational instability is the key process of angular momentum transport.. |
| 3. | K. Tomida, Masahiro Machida, T. Hosokawa, Y. Sakurai, C. H. Lin, Grand design spiral arms in a young forming circumstellar disk, 2017 Conference Francesco's Legacy: Star Formation in Space and Time, 2017.01, We study formation and long-term evolution of a circumstellar disk using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum. Although the spiral arms disappear in a few rotations, new spiral arms form recurrently throughout the Class-0 and I phases as the disk soon becomes unstable again by gas accretion. Using synthetic observation, we compare our model with a recent high-resolution observation of Elias 2-27, whose circumstellar disk has grand design spiral arms, and find good agreement. Our model suggests that the grand design spiral arms around Elias 2-27 are consistent with material arms formed by gravitational instability. If such spiral arms commonly exist in young circumstellar disks, it implies that young circumstellar disks are considerably massive and gravitational instability is the key process of angular momentum transport.. |
| 4. | K. Tomida, Masahiro Machida, T. Hosokawa, Y. Sakurai, C. H. Lin, Grand design spiral arms in a young forming circumstellar disk, 2017 Conference Francesco's Legacy: Star Formation in Space and Time, 2017.01, We study formation and long-term evolution of a circumstellar disk using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum. Although the spiral arms disappear in a few rotations, new spiral arms form recurrently throughout the Class-0 and I phases as the disk soon becomes unstable again by gas accretion. Using synthetic observation, we compare our model with a recent high-resolution observation of Elias 2-27, whose circumstellar disk has grand design spiral arms, and find good agreement. Our model suggests that the grand design spiral arms around Elias 2-27 are consistent with material arms formed by gravitational instability. If such spiral arms commonly exist in young circumstellar disks, it implies that young circumstellar disks are considerably massive and gravitational instability is the key process of angular momentum transport.. |
| 5. | K. Tomida, Masahiro Machida, T. Hosokawa, Y. Sakurai, C. H. Lin, Grand design spiral arms in a young forming circumstellar disk, 2017 Conference Francesco's Legacy: Star Formation in Space and Time, 2017.01, We study formation and long-term evolution of a circumstellar disk using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum. Although the spiral arms disappear in a few rotations, new spiral arms form recurrently throughout the Class-0 and I phases as the disk soon becomes unstable again by gas accretion. Using synthetic observation, we compare our model with a recent high-resolution observation of Elias 2-27, whose circumstellar disk has grand design spiral arms, and find good agreement. Our model suggests that the grand design spiral arms around Elias 2-27 are consistent with material arms formed by gravitational instability. If such spiral arms commonly exist in young circumstellar disks, it implies that young circumstellar disks are considerably massive and gravitational instability is the key process of angular momentum transport.. |
| 6. | S. I. Inutsuka, Masahiro Machida, T. Matsumoto, Y. Tsukamoto, K. Iwasaki, Low-Mass Star Formation From Molecular Cloud Cores to Protostars and Protoplanetary Disks, 6th Zermatt Symposium on Conditions and Impact of Star Formation: From Lab to Space 2015, 2016.05, This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in the protostellar collapse simulations cover a huge dynamic range from molecular cloud core density to stellar density in a self-consistent manner and account for all the non-ideal magnetohydrodynamical effects, such as Ohmic resistivity, ambipolar diffusion, and Hall current. We explain the emergence of the first core, i.e., the quasi-hydrostatic object that consists of molecular gas, and the second core, i.e., the protostar. Ohmic dissipation largely removes the magnetic flux from the center of a collapsing cloud core. A fast well-collimated bipolar jet along the rotation axis of the protostar is driven after the magnetic field is re-coupled with warm gas (∼103 K) around the protostar. The circumstellar disk is born in the "dead zone", a region that is de-coupled from the magnetic field, and the outer radius of the disk increases with that of the dead zone during the early accretion phase. The rapid increase of the disk size occurs after the depletion of the envelope of molecular cloud core. The effect of Hall current may create two distinct populations of protoplanetary disks.. |
| 7. | S. I. Inutsuka, Masahiro Machida, T. Matsumoto, Y. Tsukamoto, K. Iwasaki, Low-Mass Star Formation From Molecular Cloud Cores to Protostars and Protoplanetary Disks, 6th Zermatt Symposium on Conditions and Impact of Star Formation: From Lab to Space 2015, 2016.05, This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in the protostellar collapse simulations cover a huge dynamic range from molecular cloud core density to stellar density in a self-consistent manner and account for all the non-ideal magnetohydrodynamical effects, such as Ohmic resistivity, ambipolar diffusion, and Hall current. We explain the emergence of the first core, i.e., the quasi-hydrostatic object that consists of molecular gas, and the second core, i.e., the protostar. Ohmic dissipation largely removes the magnetic flux from the center of a collapsing cloud core. A fast well-collimated bipolar jet along the rotation axis of the protostar is driven after the magnetic field is re-coupled with warm gas (∼103 K) around the protostar. The circumstellar disk is born in the "dead zone", a region that is de-coupled from the magnetic field, and the outer radius of the disk increases with that of the dead zone during the early accretion phase. The rapid increase of the disk size occurs after the depletion of the envelope of molecular cloud core. The effect of Hall current may create two distinct populations of protoplanetary disks.. |
| 8. | S. I. Inutsuka, Masahiro Machida, T. Matsumoto, Y. Tsukamoto, K. Iwasaki, Low-Mass Star Formation From Molecular Cloud Cores to Protostars and Protoplanetary Disks, 6th Zermatt Symposium on Conditions and Impact of Star Formation: From Lab to Space 2015, 2016.05, This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in the protostellar collapse simulations cover a huge dynamic range from molecular cloud core density to stellar density in a self-consistent manner and account for all the non-ideal magnetohydrodynamical effects, such as Ohmic resistivity, ambipolar diffusion, and Hall current. We explain the emergence of the first core, i.e., the quasi-hydrostatic object that consists of molecular gas, and the second core, i.e., the protostar. Ohmic dissipation largely removes the magnetic flux from the center of a collapsing cloud core. A fast well-collimated bipolar jet along the rotation axis of the protostar is driven after the magnetic field is re-coupled with warm gas (∼103 K) around the protostar. The circumstellar disk is born in the "dead zone", a region that is de-coupled from the magnetic field, and the outer radius of the disk increases with that of the dead zone during the early accretion phase. The rapid increase of the disk size occurs after the depletion of the envelope of molecular cloud core. The effect of Hall current may create two distinct populations of protoplanetary disks.. |
| 9. | S. I. Inutsuka, Masahiro Machida, T. Matsumoto, Y. Tsukamoto, K. Iwasaki, Low-Mass Star Formation From Molecular Cloud Cores to Protostars and Protoplanetary Disks, 6th Zermatt Symposium on Conditions and Impact of Star Formation: From Lab to Space 2015, 2016.05, This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in the protostellar collapse simulations cover a huge dynamic range from molecular cloud core density to stellar density in a self-consistent manner and account for all the non-ideal magnetohydrodynamical effects, such as Ohmic resistivity, ambipolar diffusion, and Hall current. We explain the emergence of the first core, i.e., the quasi-hydrostatic object that consists of molecular gas, and the second core, i.e., the protostar. Ohmic dissipation largely removes the magnetic flux from the center of a collapsing cloud core. A fast well-collimated bipolar jet along the rotation axis of the protostar is driven after the magnetic field is re-coupled with warm gas (∼103 K) around the protostar. The circumstellar disk is born in the "dead zone", a region that is de-coupled from the magnetic field, and the outer radius of the disk increases with that of the dead zone during the early accretion phase. The rapid increase of the disk size occurs after the depletion of the envelope of molecular cloud core. The effect of Hall current may create two distinct populations of protoplanetary disks.. |
| 10. | Kohji Tomisaka, Akimasa Kataoka, Masahiro Machida, Kengo Tomida, Kazuya Saigo, Expected observations of star formation process From molecular cloud core to first hydrostatic core, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01, We performed MHD simulations of the contraction of rotating, magnetized molecular cloud cores. In the molecular cores, B-field and angular momentum (J) vector are not always aligned. When a first hydrostatic core forms, axisymmetric structure appears and average B and J are parallel in small scale. However, in large scale, the configuration is far from this. This means that contraction process is imprinted on the snapshot. We calculated two mock observations of MHD simulations (1) the polarization of dust thermal emission to reveal the magnetic evolution and (2) the line emissions from interstellar molecules to reveal the evolution of density and velocity. Comparing the mock observations with true ones, we can answer several questions: in which case the hourglass-shaped and S-shaped magnetic fields are seen; how the distribution of polarized intensity is understood; how the first hydrostatic core should be observationally identified.. |
| 11. | Takayuki Kotani, Motohide Tamura, Hiroshi Suto, Jun Nishikawa, Bun'Ei Sato, Wako Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo Nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shane Jacobson, Jun Hashimoto, Jun Ichi Morino, Yasushi Okuyama, Yosuke Tanaka, Shota Suzuki, Sadahiro Inoue, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma, Yasunori Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H. Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara, Tomoyasu Yamamuro, Infrared Doppler instrument (IRD) for the Subaru telescope to search for Earth-like planets around nearby M-dwarfs, Ground-Based and Airborne Instrumentation for Astronomy V, 2014.01, We report the current status of the Infrared Doppler (IRD) instrument for the Subaru telescope, which aims at detecting Earth-like planets around nearby M darwfs via the radial velocity (RV) measurements. IRD is a fiber-fed, near infrared spectrometer which enables us to obtain high-resolution spectrum (R∼70000) from 0.97 to 1.75 μm. We have been developing new technologies to achieve 1m/s RV measurement precision, including an original laser frequency comb as an extremely stable wavelength standard in the near infrared. To achieve ultimate thermal stability, very low thermal expansion ceramic is used for most of the optical components including the optical bench.. |
| 12. | Yusuke Tsukamoto, Masahiro Machida, Shu Ichiro Inutsuka, The effect of mass accretion for formation and thermal evolution of circumstellar disks, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01. |
| 13. | Kohji Tomisaka, Akimasa Kataoka, Masahiro Machida, Kengo Tomida, Kazuya Saigo, Expected observations of star formation process From molecular cloud core to first hydrostatic core, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01, We performed MHD simulations of the contraction of rotating, magnetized molecular cloud cores. In the molecular cores, B-field and angular momentum (J) vector are not always aligned. When a first hydrostatic core forms, axisymmetric structure appears and average B and J are parallel in small scale. However, in large scale, the configuration is far from this. This means that contraction process is imprinted on the snapshot. We calculated two mock observations of MHD simulations (1) the polarization of dust thermal emission to reveal the magnetic evolution and (2) the line emissions from interstellar molecules to reveal the evolution of density and velocity. Comparing the mock observations with true ones, we can answer several questions: in which case the hourglass-shaped and S-shaped magnetic fields are seen; how the distribution of polarized intensity is understood; how the first hydrostatic core should be observationally identified.. |
| 14. | Takayuki Kotani, Motohide Tamura, Hiroshi Suto, Jun Nishikawa, Bun'Ei Sato, Wako Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo Nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shane Jacobson, Jun Hashimoto, Jun Ichi Morino, Yasushi Okuyama, Yosuke Tanaka, Shota Suzuki, Sadahiro Inoue, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma, Yasunori Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H. Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara, Tomoyasu Yamamuro, Infrared Doppler instrument (IRD) for the Subaru telescope to search for Earth-like planets around nearby M-dwarfs, Ground-Based and Airborne Instrumentation for Astronomy V, 2014.01, We report the current status of the Infrared Doppler (IRD) instrument for the Subaru telescope, which aims at detecting Earth-like planets around nearby M darwfs via the radial velocity (RV) measurements. IRD is a fiber-fed, near infrared spectrometer which enables us to obtain high-resolution spectrum (R∼70000) from 0.97 to 1.75 μm. We have been developing new technologies to achieve 1m/s RV measurement precision, including an original laser frequency comb as an extremely stable wavelength standard in the near infrared. To achieve ultimate thermal stability, very low thermal expansion ceramic is used for most of the optical components including the optical bench.. |
| 15. | Yusuke Tsukamoto, Masahiro Machida, Shu Ichiro Inutsuka, The effect of mass accretion for formation and thermal evolution of circumstellar disks, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01. |
| 16. | Kohji Tomisaka, Akimasa Kataoka, Masahiro Machida, Kengo Tomida, Kazuya Saigo, Expected observations of star formation process From molecular cloud core to first hydrostatic core, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01, We performed MHD simulations of the contraction of rotating, magnetized molecular cloud cores. In the molecular cores, B-field and angular momentum (J) vector are not always aligned. When a first hydrostatic core forms, axisymmetric structure appears and average B and J are parallel in small scale. However, in large scale, the configuration is far from this. This means that contraction process is imprinted on the snapshot. We calculated two mock observations of MHD simulations (1) the polarization of dust thermal emission to reveal the magnetic evolution and (2) the line emissions from interstellar molecules to reveal the evolution of density and velocity. Comparing the mock observations with true ones, we can answer several questions: in which case the hourglass-shaped and S-shaped magnetic fields are seen; how the distribution of polarized intensity is understood; how the first hydrostatic core should be observationally identified.. |
| 17. | Takayuki Kotani, Motohide Tamura, Hiroshi Suto, Jun Nishikawa, Bun'Ei Sato, Wako Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo Nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shane Jacobson, Jun Hashimoto, Jun Ichi Morino, Yasushi Okuyama, Yosuke Tanaka, Shota Suzuki, Sadahiro Inoue, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma, Yasunori Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H. Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara, Tomoyasu Yamamuro, Infrared Doppler instrument (IRD) for the Subaru telescope to search for Earth-like planets around nearby M-dwarfs, Ground-Based and Airborne Instrumentation for Astronomy V, 2014.01, We report the current status of the Infrared Doppler (IRD) instrument for the Subaru telescope, which aims at detecting Earth-like planets around nearby M darwfs via the radial velocity (RV) measurements. IRD is a fiber-fed, near infrared spectrometer which enables us to obtain high-resolution spectrum (R∼70000) from 0.97 to 1.75 μm. We have been developing new technologies to achieve 1m/s RV measurement precision, including an original laser frequency comb as an extremely stable wavelength standard in the near infrared. To achieve ultimate thermal stability, very low thermal expansion ceramic is used for most of the optical components including the optical bench.. |
| 18. | Yusuke Tsukamoto, Masahiro Machida, Shu Ichiro Inutsuka, The effect of mass accretion for formation and thermal evolution of circumstellar disks, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01. |
| 19. | Kohji Tomisaka, Akimasa Kataoka, Masahiro Machida, Kengo Tomida, Kazuya Saigo, Expected observations of star formation process From molecular cloud core to first hydrostatic core, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01, We performed MHD simulations of the contraction of rotating, magnetized molecular cloud cores. In the molecular cores, B-field and angular momentum (J) vector are not always aligned. When a first hydrostatic core forms, axisymmetric structure appears and average B and J are parallel in small scale. However, in large scale, the configuration is far from this. This means that contraction process is imprinted on the snapshot. We calculated two mock observations of MHD simulations (1) the polarization of dust thermal emission to reveal the magnetic evolution and (2) the line emissions from interstellar molecules to reveal the evolution of density and velocity. Comparing the mock observations with true ones, we can answer several questions: in which case the hourglass-shaped and S-shaped magnetic fields are seen; how the distribution of polarized intensity is understood; how the first hydrostatic core should be observationally identified.. |
| 20. | Takayuki Kotani, Motohide Tamura, Hiroshi Suto, Jun Nishikawa, Bun'Ei Sato, Wako Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo Nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shane Jacobson, Jun Hashimoto, Jun Ichi Morino, Yasushi Okuyama, Yosuke Tanaka, Shota Suzuki, Sadahiro Inoue, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma, Yasunori Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H. Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara, Tomoyasu Yamamuro, Infrared Doppler instrument (IRD) for the Subaru telescope to search for Earth-like planets around nearby M-dwarfs, Ground-Based and Airborne Instrumentation for Astronomy V, 2014.01, We report the current status of the Infrared Doppler (IRD) instrument for the Subaru telescope, which aims at detecting Earth-like planets around nearby M darwfs via the radial velocity (RV) measurements. IRD is a fiber-fed, near infrared spectrometer which enables us to obtain high-resolution spectrum (R∼70000) from 0.97 to 1.75 μm. We have been developing new technologies to achieve 1m/s RV measurement precision, including an original laser frequency comb as an extremely stable wavelength standard in the near infrared. To achieve ultimate thermal stability, very low thermal expansion ceramic is used for most of the optical components including the optical bench.. |
| 21. | Yusuke Tsukamoto, Masahiro Machida, Shu Ichiro Inutsuka, The effect of mass accretion for formation and thermal evolution of circumstellar disks, Conference on Labyrinth of Star Formation dedicated to Prof. Anthony Whitworth, 2012, 2014.01. |
| 22. | M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Y. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, Masahiro Machida, T. Matsuo, T. Nagata, Y. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada, Infrared Doppler instrument for the Subaru telescope (IRD), Ground-Based and Airborne Instrumentation for Astronomy IV, 2012.12, IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. It is a relatively compact (~1m size) spectrometer with a new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined with an original frequency comb using optical pulse synthesizer. The spectrometer will employ a 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both the telescope/Adaptive Optics and comb beams are fed to the spectrometer via optical fibers, while the instrument is placed at the Nasmyth platform of the Subaru telescope. Expected accuracy of the Doppler-shifted velocity measurements is about 1 m s-1. Helped with the large collecting area and high image quality of the Subaru telescope, IRD can conduct systematic radial velocity surveys of nearby middle-to-late M stars aiming for down to one Earth-mass planet. Systematic observational and theoretical studies of M stars and their planets for the IRD science are also ongoing. We will report the design and preliminary development progresses of the whole and each component of IRD.. |
| 23. | M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Y. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, Masahiro Machida, T. Matsuo, T. Nagata, Y. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada, Infrared Doppler instrument for the Subaru telescope (IRD), Ground-Based and Airborne Instrumentation for Astronomy IV, 2012.12, IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. It is a relatively compact (~1m size) spectrometer with a new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined with an original frequency comb using optical pulse synthesizer. The spectrometer will employ a 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both the telescope/Adaptive Optics and comb beams are fed to the spectrometer via optical fibers, while the instrument is placed at the Nasmyth platform of the Subaru telescope. Expected accuracy of the Doppler-shifted velocity measurements is about 1 m s-1. Helped with the large collecting area and high image quality of the Subaru telescope, IRD can conduct systematic radial velocity surveys of nearby middle-to-late M stars aiming for down to one Earth-mass planet. Systematic observational and theoretical studies of M stars and their planets for the IRD science are also ongoing. We will report the design and preliminary development progresses of the whole and each component of IRD.. |
| 24. | M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Y. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, Masahiro Machida, T. Matsuo, T. Nagata, Y. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada, Infrared Doppler instrument for the Subaru telescope (IRD), Ground-Based and Airborne Instrumentation for Astronomy IV, 2012.12, IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. It is a relatively compact (~1m size) spectrometer with a new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined with an original frequency comb using optical pulse synthesizer. The spectrometer will employ a 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both the telescope/Adaptive Optics and comb beams are fed to the spectrometer via optical fibers, while the instrument is placed at the Nasmyth platform of the Subaru telescope. Expected accuracy of the Doppler-shifted velocity measurements is about 1 m s-1. Helped with the large collecting area and high image quality of the Subaru telescope, IRD can conduct systematic radial velocity surveys of nearby middle-to-late M stars aiming for down to one Earth-mass planet. Systematic observational and theoretical studies of M stars and their planets for the IRD science are also ongoing. We will report the design and preliminary development progresses of the whole and each component of IRD.. |
| 25. | M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Y. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, Masahiro Machida, T. Matsuo, T. Nagata, Y. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada, Infrared Doppler instrument for the Subaru telescope (IRD), Ground-Based and Airborne Instrumentation for Astronomy IV, 2012.12, IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. It is a relatively compact (~1m size) spectrometer with a new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined with an original frequency comb using optical pulse synthesizer. The spectrometer will employ a 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both the telescope/Adaptive Optics and comb beams are fed to the spectrometer via optical fibers, while the instrument is placed at the Nasmyth platform of the Subaru telescope. Expected accuracy of the Doppler-shifted velocity measurements is about 1 m s-1. Helped with the large collecting area and high image quality of the Subaru telescope, IRD can conduct systematic radial velocity surveys of nearby middle-to-late M stars aiming for down to one Earth-mass planet. Systematic observational and theoretical studies of M stars and their planets for the IRD science are also ongoing. We will report the design and preliminary development progresses of the whole and each component of IRD.. |
| 26. | Masahiro Machida, Recent developments in simulations of low-mass star formation, 2011.04, In star forming regions, we can observe different evolutionary stages of various objects and phenomena such as molecular clouds, protostellar jets and outflows, circumstellar disks, and protostars. However, it is difficult to directly observe the star formation process itself, because it is veiled by the dense infalling envelope. Numerical simulations can unveil the star formation process in the collapsing gas cloud. Recently, some studies showed protostar formation from the prestellar core stage, in which both molecular clouds and protostars are resolved with sufficient spatial resolution. These simulations showed fragmentation and binary formation, outflow and jet driving, and circumstellar disk formation in the collapsing gas clouds. In addition, the angular momentum transfer and dissipation process of the magnetic field in the star formation process were investigated. In this paper, I review recent developments in numerical simulations of low-mass star formation.. |
| 27. | Masahiro Machida, Recent developments in simulations of low-mass star formation, 2011.04, In star forming regions, we can observe different evolutionary stages of various objects and phenomena such as molecular clouds, protostellar jets and outflows, circumstellar disks, and protostars. However, it is difficult to directly observe the star formation process itself, because it is veiled by the dense infalling envelope. Numerical simulations can unveil the star formation process in the collapsing gas cloud. Recently, some studies showed protostar formation from the prestellar core stage, in which both molecular clouds and protostars are resolved with sufficient spatial resolution. These simulations showed fragmentation and binary formation, outflow and jet driving, and circumstellar disk formation in the collapsing gas clouds. In addition, the angular momentum transfer and dissipation process of the magnetic field in the star formation process were investigated. In this paper, I review recent developments in numerical simulations of low-mass star formation.. |
| 28. | Masahiro Machida, Recent developments in simulations of low-mass star formation, 2011.04, In star forming regions, we can observe different evolutionary stages of various objects and phenomena such as molecular clouds, protostellar jets and outflows, circumstellar disks, and protostars. However, it is difficult to directly observe the star formation process itself, because it is veiled by the dense infalling envelope. Numerical simulations can unveil the star formation process in the collapsing gas cloud. Recently, some studies showed protostar formation from the prestellar core stage, in which both molecular clouds and protostars are resolved with sufficient spatial resolution. These simulations showed fragmentation and binary formation, outflow and jet driving, and circumstellar disk formation in the collapsing gas clouds. In addition, the angular momentum transfer and dissipation process of the magnetic field in the star formation process were investigated. In this paper, I review recent developments in numerical simulations of low-mass star formation.. |
| 29. | Masahiro Machida, Recent developments in simulations of low-mass star formation, 2011.04, In star forming regions, we can observe different evolutionary stages of various objects and phenomena such as molecular clouds, protostellar jets and outflows, circumstellar disks, and protostars. However, it is difficult to directly observe the star formation process itself, because it is veiled by the dense infalling envelope. Numerical simulations can unveil the star formation process in the collapsing gas cloud. Recently, some studies showed protostar formation from the prestellar core stage, in which both molecular clouds and protostars are resolved with sufficient spatial resolution. These simulations showed fragmentation and binary formation, outflow and jet driving, and circumstellar disk formation in the collapsing gas clouds. In addition, the angular momentum transfer and dissipation process of the magnetic field in the star formation process were investigated. In this paper, I review recent developments in numerical simulations of low-mass star formation.. |
| 30. | , [URL]. |
| 31. | Masahiro Machida, Kazuyuki Omukai, Tomoaki Matsumoto, Magnetohy drodynamics of Population III star formation, 1st Stars and Galaxies: Challenges for the Next Decade, 2010.12, The evolution of collapsing primordial clouds and the formation of Population III (Pop III) protostars are investigated with three-dimensional ideal MHD simulations. We follow the collapse of parsec-sized primordial clouds down to the formation of protostars on sub-AU scales. Pop III protostar formation is characterized by the ratio of rotational to magnetic energy of the natal cloud. When the rotational energy is larger than the magnetic energy, fragmentation occurs prior to the formation of the protostar, and a binary or multiple system appears. When the magnetic energy is greater than the rotational energy, a strong (> 100 km s-1) jet is driven by the circumstellar disk around the protostar, which does not fragment. Thus, even in the early universe, magnetic fields play an important role in the star formation process.. |
| 32. | Masahiro Machida, Kazuyuki Omukai, Tomoaki Matsumoto, Magnetohy drodynamics of Population III star formation, 1st Stars and Galaxies: Challenges for the Next Decade, 2010.12, The evolution of collapsing primordial clouds and the formation of Population III (Pop III) protostars are investigated with three-dimensional ideal MHD simulations. We follow the collapse of parsec-sized primordial clouds down to the formation of protostars on sub-AU scales. Pop III protostar formation is characterized by the ratio of rotational to magnetic energy of the natal cloud. When the rotational energy is larger than the magnetic energy, fragmentation occurs prior to the formation of the protostar, and a binary or multiple system appears. When the magnetic energy is greater than the rotational energy, a strong (> 100 km s-1) jet is driven by the circumstellar disk around the protostar, which does not fragment. Thus, even in the early universe, magnetic fields play an important role in the star formation process.. |
| 33. | Masahiro Machida, Kazuyuki Omukai, Tomoaki Matsumoto, Magnetohy drodynamics of Population III star formation, 1st Stars and Galaxies: Challenges for the Next Decade, 2010.12, The evolution of collapsing primordial clouds and the formation of Population III (Pop III) protostars are investigated with three-dimensional ideal MHD simulations. We follow the collapse of parsec-sized primordial clouds down to the formation of protostars on sub-AU scales. Pop III protostar formation is characterized by the ratio of rotational to magnetic energy of the natal cloud. When the rotational energy is larger than the magnetic energy, fragmentation occurs prior to the formation of the protostar, and a binary or multiple system appears. When the magnetic energy is greater than the rotational energy, a strong (> 100 km s-1) jet is driven by the circumstellar disk around the protostar, which does not fragment. Thus, even in the early universe, magnetic fields play an important role in the star formation process.. |
| 34. | Masahiro Machida, Kazuyuki Omukai, Tomoaki Matsumoto, Magnetohy drodynamics of Population III star formation, 1st Stars and Galaxies: Challenges for the Next Decade, 2010.12, The evolution of collapsing primordial clouds and the formation of Population III (Pop III) protostars are investigated with three-dimensional ideal MHD simulations. We follow the collapse of parsec-sized primordial clouds down to the formation of protostars on sub-AU scales. Pop III protostar formation is characterized by the ratio of rotational to magnetic energy of the natal cloud. When the rotational energy is larger than the magnetic energy, fragmentation occurs prior to the formation of the protostar, and a binary or multiple system appears. When the magnetic energy is greater than the rotational energy, a strong (> 100 km s-1) jet is driven by the circumstellar disk around the protostar, which does not fragment. Thus, even in the early universe, magnetic fields play an important role in the star formation process.. |
| 35. | , [URL]. |
| 36. | , [URL]. |
| 37. | , [URL]. |
| 38. | Tomoaki Matsumoto, Masahiro Machida, Kohji Tomisaka, Tomoyuki Hanawa, Self-gravitational collapse of a magnetized cloud core High resolution simulations with three-dimensional MHD nested grid, Proceedings of the 18th International Conference, 2004.12, We investigate self-gravitational collapse of magnetized molecular cloud cores and formation of the outflow. We employ a nested grid in order to resolve fine structures of protostar and outflow generation, of which size is as small as 1 AU, and to follow the whole structure of the molecular cloud core, of which radius reaches 0.1-1 pc, simultaneously. The nested grid allows us to follow the evolution of the cloud core with the high dynamic range of 105-106 in the spatial resolution. In this paper, we introduce implementations of the self-gravitational MHD nested grid code and show applications to early stages in star formation: gravitational collapse of cloud core, "first core" formation, and bipolar outflow ejection. In both cases of single and binary star formation, magnetic fields play important role in the outflow formation. The outflow region has extremely low beta regions of β= 10 -6-10-3, and our code shows no sign of numerical instability even in these low-beta regions.. |
| 39. | Tomoaki Matsumoto, Masahiro Machida, Kohji Tomisaka, Tomoyuki Hanawa, Self-gravitational collapse of a magnetized cloud core High resolution simulations with three-dimensional MHD nested grid, Proceedings of the 18th International Conference, 2004.12, We investigate self-gravitational collapse of magnetized molecular cloud cores and formation of the outflow. We employ a nested grid in order to resolve fine structures of protostar and outflow generation, of which size is as small as 1 AU, and to follow the whole structure of the molecular cloud core, of which radius reaches 0.1-1 pc, simultaneously. The nested grid allows us to follow the evolution of the cloud core with the high dynamic range of 105-106 in the spatial resolution. In this paper, we introduce implementations of the self-gravitational MHD nested grid code and show applications to early stages in star formation: gravitational collapse of cloud core, "first core" formation, and bipolar outflow ejection. In both cases of single and binary star formation, magnetic fields play important role in the outflow formation. The outflow region has extremely low beta regions of β= 10 -6-10-3, and our code shows no sign of numerical instability even in these low-beta regions.. |
| 40. | Tomoaki Matsumoto, Masahiro Machida, Kohji Tomisaka, Tomoyuki Hanawa, Self-gravitational collapse of a magnetized cloud core High resolution simulations with three-dimensional MHD nested grid, Proceedings of the 18th International Conference, 2004.12, We investigate self-gravitational collapse of magnetized molecular cloud cores and formation of the outflow. We employ a nested grid in order to resolve fine structures of protostar and outflow generation, of which size is as small as 1 AU, and to follow the whole structure of the molecular cloud core, of which radius reaches 0.1-1 pc, simultaneously. The nested grid allows us to follow the evolution of the cloud core with the high dynamic range of 105-106 in the spatial resolution. In this paper, we introduce implementations of the self-gravitational MHD nested grid code and show applications to early stages in star formation: gravitational collapse of cloud core, "first core" formation, and bipolar outflow ejection. In both cases of single and binary star formation, magnetic fields play important role in the outflow formation. The outflow region has extremely low beta regions of β= 10 -6-10-3, and our code shows no sign of numerical instability even in these low-beta regions.. |
| 41. | Tomoaki Matsumoto, Masahiro Machida, Kohji Tomisaka, Tomoyuki Hanawa, Self-gravitational collapse of a magnetized cloud core High resolution simulations with three-dimensional MHD nested grid, Proceedings of the 18th International Conference, 2004.12, We investigate self-gravitational collapse of magnetized molecular cloud cores and formation of the outflow. We employ a nested grid in order to resolve fine structures of protostar and outflow generation, of which size is as small as 1 AU, and to follow the whole structure of the molecular cloud core, of which radius reaches 0.1-1 pc, simultaneously. The nested grid allows us to follow the evolution of the cloud core with the high dynamic range of 105-106 in the spatial resolution. In this paper, we introduce implementations of the self-gravitational MHD nested grid code and show applications to early stages in star formation: gravitational collapse of cloud core, "first core" formation, and bipolar outflow ejection. In both cases of single and binary star formation, magnetic fields play important role in the outflow formation. The outflow region has extremely low beta regions of β= 10 -6-10-3, and our code shows no sign of numerical instability even in these low-beta regions.. |
| 42. | , [URL]. |
| 43. | , [URL]. |
| 44. | , [URL]. |
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