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Words near each other
・ NGC 5775
・ NGC 5792
・ NGC 5806
・ NGC 5820
・ NGC 5821
・ NGC 5822
・ NGC 5823
・ NGC 5824
・ NGC 5829
・ NGC 4526
・ NGC 4527
・ NGC 4534
・ NGC 4535
・ NGC 4536
・ NGC 4550
NGC 4555
・ NGC 4559
・ NGC 4565
・ NGC 4567 and NGC 4568
・ NGC 457
・ NGC 4571
・ NGC 46
・ NGC 4603
・ NGC 4605
・ NGC 4609
・ NGC 4618
・ NGC 462
・ NGC 4622
・ NGC 4625
・ NGC 4627


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NGC 4555 : ウィキペディア英語版
NGC 4555

NGC 4555 is a solitary elliptical galaxy about 40,000 parsecs (125,000 light-years) across, and about 310 million light years distant. Observations by the Chandra X-ray Observatory have shown it to be surrounded by a halo of hot gas about 120,000 parsecs across. The hot gas has a temperature of around 10,000,000 kelvins. The galaxy is one of the few elliptical galaxies proven to have significant amounts of dark matter. Large amounts of dark matter are necessary to prevent the gas from escaping the galaxy; the visible mass clearly is not large enough to hold such an extensive gas halo. The dark matter halo is estimated to have 10 times the mass of the stars in the galaxy.
NGC 4555 is important because of its isolation. Most elliptical galaxies are found in the cores of groups and clusters of galaxies, and almost all those for which dark matter estimates are available are located in the centres of these larger systems. In these circumstances it impossible to know whether the dark matter is associated with the galaxy or the surrounding cluster. NGC 4555, as a field galaxy is not part of any group or cluster, and therefore provides strong evidence that dark matter can be associated with individual ellipticals.
==References==



抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)
ウィキペディアで「NGC 4555」の詳細全文を読む



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