| Project/Area Number |
08640319
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | Yamagata University |
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Principal Investigator |
UMEBAYASHI Toyoharu Yamagata University, Computing Service Center, Associate Professor, 総合情報処理センター, 助教授 (60183753)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Interstellar Molecules / Dark Clouds / Star Formation / Reaction Network / Protoplanetary Disks / Chemical Evolution / イオン・分子反応 |
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| Research Abstract |
We investigate the evolution of molecular abundance both in dark interstellar clouds and in circumstellar disks around pre-main-sequence stars.
1.We extend considerably the gaa-phase reaction network model in dark clouds to include 372 species which consist of 10 major elements and 4095 reactions. This model contains most of the species important in observational study of interstellar chemistry and a new version of database contains the latest values of reaction-rate coefficients.
2.Using the reaction models mentioned above, we calculate numerically the pseudo-time-dependent evolution of molecular abundance in various models of dark clouds. The results show that gas-phase reactions can produce observed abundance of complex molecules such as hydrocarbon radicals and cyanopolyynes under a certain physical condition of density and temperature. Model which has low metallic elemental abundance and high ion-polar neutral rate coefficients is the most feasible one of reaction network.
3.We investigate the evolution of molecular abundance in gaseous disks that are presumed to be around protostars and T Tauri stars. The reaction network we use consists of gas-phase reactions, adsorption onto dust grains and thermal desorption from grains. A considerable amount of carbon and nitrogen is locked up in the ice mantle, and oxidized (CO_2) ice and reduced (NH_3) ice naturally coexist in low temperature region of the disk.
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