| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
We analyzed, in collaboration with Britisch astronomers, the imaging and spectroscopic data of the Coma cluster of galaxies taken in 1998 with the 4.2-m William Herschel Telescope. The data are suitable to investigation of properties of galaxies under different environments because the observed areas cover a wide region from the cluster center to the outskirt.
We detected some 3000 galaxies down to R=20 mag from the imaging data. A catalog have been compiled for those detected galaxies which includes position, magnitude, (B-R) color, and effective surface brightness, effective radius, and profile shape parameters that characterize the surface brightness distribution. We identified about 450 certain members on the basis of our spectroscopy as well as the data in the literature. Another catalog has been compiled for 301 galaxies for which we made spectroscopy, which gives some absorption line indices including Mg2 and Hb. These catalogs are the largest homogeneous catalogs of confirmed me
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mber of the Coma cluster. They will be published soon.
On the basis of these catalogs, we have found the following for dwarf galaxies comprising the faint end of the luminosity function :
(1) There was no sign of difference according to the distance from the cluster center in the effective surface brightness, effective radius, and profile shape parameter of dwarf galaxies. This means that different environments in the cluster do not affect the surface brightness distribution, that is, the basic structure of dwarf galaxies.
(2) Dwarf galaxies tend to become bluer from the cluster center towards the outskirt. This is probably due to metallicity difference.
Further, for all the member galaxies we have found,
(3) In the large magitude range from giant galaxies (R=13 mag) to dwarf galaxies (R=19 mag), (a) metallicity sensitive lines get weaker for fainter galaxies, and (b) age-sensitive lines get stronger for fainter galaxies.
(4) Average age of dwarf galaxies is younger than ginat galaxies. Further, to compare with the luminosity function of the cluster galaxies,
(5) We derived the accurate luminosity function of field galaxies. Less
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