1999 Fiscal Year Final Research Report Summary
Precision distance to Galactic Cepheid variables with infrared observation
| Project/Area Number |
10640225
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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 | Institute for Cosmic Ray Research, University of Tokyo |
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Principal Investigator |
SEKIGUCHI Maki University of Tokyo, Institute for Cosmic Ray Research, Associate Professor, 宇宙線研究所, 助教授 (40216528)
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| Co-Investigator(Kenkyū-buntansha) |
ICHIKAWA Takashi Tohoku University , Faculty of Science, Associate Professor, 理学部, 助教授 (80212992)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Cepheid variables / distance determination |
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| Research Abstract |
We have installed an existing 40cm telescope tube onto the purchased mount resulting in fully automatic observation, No other system exists for infrared observing of stellar-clusters with Cepheid variables, We installed an existing IR-camera to the telescope. We improved the camera's cooling capacity for longer automatic observation. After observing several clusters, we found that singal-to-noise ratio of that camera is five times worse than expected. This noise problem allows us to observe clusters only within 1 Kpc. We therefore focused our analysis on M25 and NGC1647 and found that the error contribution from dust absorption was reduced by a factor of four compared to previous observation in visible wavelength. Parallel to the observation, we put emphasis on the improvement of isochrone and on importance of metallicity. We found the existing B-V transformation contains large uncertainty. Using the modern updated database and metallicity-dependence, we derived better revised B-V transformation (AJ in press). As far the metallicity, we derived a new formula to estimate metallicity from UBV photometory (in preparation).
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