| Project/Area Number |
09640312
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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 | The University of Tokyo |
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Principal Investigator |
OKAMURA Sadanori The University of Tokyo, Graduate School of Science : Professor, 大学院・理学系研究科, 教授 (20114423)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Dwarf Galaxies / Cluster of Galaxies / Cluster Environment / スペース観測 |
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| Research Abstract |
We obtained spectra of about 500 dwarf galaxies in the Coma cluster in April 1998 using the 4.2-m William Hcrschel Telescope (WHT) at La Palma. In May 1998, we brought our mosaic CCD camera into WHT and obtained imaging data of Coma, Virgo, and Hercules clusters at the prime focus of WHT.
First data analysis was made for Coma cluster, and the results were compared with Virgo cluster. Coma cluster is a rich regular cluster containing few spiral galaxies while Virgo cluster is a poor irregular and spiral-rich cluster.
The comparison revealed the following. First, dwarf galaxies in Coma cluster shows the exponential radial luminosity profile, which is the same characteristic found in Virgo dwarf galaxies. Second, Coma dwarf galaxies follow the same luminosity versus surface brightness relation found for Virgo dwarf galaxies. These two findings indicate that dwarf galaxies in two very different cluster environments show similar properties. There are two alternative models about the formation of dwarf galaxies. Properties of dwarf galaxies are mostly determined at the time of their formation according to the one model while their properties are largely modified by the galaxy-galaxy and/or galaxy-intergalactic medium interactions in the cluster according to the other. Our findings support the former.
We have found that dwarf galaxies show the color-magnitude relation similar to giant galaxies and that the slope of the relation depends upon the aperture size.
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