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| | The Local Group (Site not responding. Last check: 2007-11-06) |
 | | The vast clouds of cool hydrogen gas which envelop galaxies are not visible in optical, ultraviolet or infrared images; but by superimposing a radio map (shown in blue) of the 21-centimeter radiation of hydrogen on an optical image of M33, the hidden becomes visible. |
 | | If such stars did not exist, the galaxies would be much fainter, and in so-called elliptical galaxies stars exist in large numbers, but no hot, bright stars have recently formed, making such galaxies far fainter and less impressive than their masses would warrant. |
 | | Until recently, it was suspected that such metal-poor galaxies were very old, but because of their small size, it seemed possible that they might have formed so recently that their stars simply hadn't had a chance to develop heavy metals yet. |
| cseligman.com /text/galaxies/local.htm (1267 words) |
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