2005 Fiscal Year Final Research Report Summary
Phase Interchange of Galactic Interstellar Gas Explored by the Terahertz Heterodyne Sensing
| Project/Area Number |
14204013
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | The University of Tokyo |
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Principal Investigator |
YAMAMOTO Satoshi The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (80182624)
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| Co-Investigator(Kenkyū-buntansha) |
OKA Tomoharu The University of Tokyo, Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (10291056)
NOGUCHI Takeshi National Astronomy Observatory of Japan, Radioastronomy Division, Associate Professor, 電波天文学研究系, 助教授 (90237826)
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| Project Period (FY) |
2002 – 2005
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| Keywords | Star Formation / Submillimeter-wave / Molecular Cloud / Galaxy / Radio Telescope / Atomic Carbon / Terahertz / Superconductor |
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| Research Abstract |
In this study, we focused on the phase interchange of interstellar gas in the Galaxy, and conducted the following two researches.
The first one is a development of the THz heterodyne receiver using the superconductive HEB mixer in order to explore the distribution of the nitrogen ion line (1.46THz). With this line, we can study a role of plasma gas in formation and evolution of molecular clouds. By using the facilities at Nobeyama Radio Observatory, we have fabricated a diffusion cooled HEB mixer element which has a microbridge structure of Nb with a size of a few 100nm. After many trials, we finally established the fabrication process using the liftoff method. The mixer element was mounted on the waveguide mixer block for the RF test, and we have confirmed the mixer operation at 800GHz. Although we have still some problems to overcome, we were able to form a strong base toward realizing the HEB mixer receiver for the THz astronomy.
Along with the above development study, we studied formation and evolution of molecular clouds by observing the fine structure line of the atomic carbon with the Mount Fuji submillimeter-wave telescope. Particularly, we observed bright rimmed globules, which are illuminated by strong UV radiation from a nearby OB stars. In a young bright rimmed globule, IC1396, we found that the distribution of the atomic carbon extends over the entire of the clouds, not concentrating at the bright rim. On the other hand, we found a peak of the atomic carbon emission at the bright rim position in a rather old globule, λ Ori. This indicates that the atomic carbon gradually changes into CO as the cloud evolves, and that it only exists in the PDR layer illuminated by OB stars. Therefore we further confirmed that the atomic carbon can be a good tracer to study formation and evolution of molecular clouds.
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