2003 Fiscal Year Final Research Report Summary
Star Formation and Chemical Evolution in Population II Interstellar Clouds
| Project/Area Number |
14540222
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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 |
YMEBAYASHI 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) |
2002 – 2003
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| Keywords | Interstellar Clouds / Star Formation / Interstellar Molecules / Magnetic Fields / Chemical Evolution / Pupulation II |
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| Research Abstract |
We investigate the physical and chemical evolution of interstellar gas clouds with low fractional abundance of heavy elements (population II composition), and obtain the following results.
1.We investigate the detailed processes at work in the drift of magnetic fields in molecular clouds taking into account small charges grains. We find that grains play a decisive role in the process of magnetic flux loss and that the magnetic fields effectively decouple from the gas, reminiscent of Ohmic dissipation, though flux loss occurs about 10 times faster than by pure Ohmic dissipation.
2.We investigate the ionization by the decay of radioactive elements in interstellar material. Among the elements whose half-lives are longer than about a billion year, ^<40>K, ^<235>U and ^<238>U are major source of ionization in later stage of star formation. If short-lived elements exist in interstellar material, ^<26>Al, ^<41>Ca, ^<53>Mn and ^<60>Fe can be the important source for ionization.
3.Using the reaction models in dark clouds, we calculate numerically the pseudo-time-dependent evolution of molecular abundances in the cloud of the gas temperature up to 50K. The results show that the effect of gas temperature is less than that of the metal abundance in gas phase. We now construct a gas-phase reaction network model in population II gas clouds where the temperature can be higher than 100K.
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Research Products
(4 results)
