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新发现的星系几乎完全是由暗物质

Both images show the Dragonfly 44 dark galaxy, only on the left it大发官方娱乐’;s much fainter (Sloan Digital Sky Survey), while the on the right (Gemini telescope) was taken with a very long exposure。 Credit Pieter van Dokkum, Roberto Abraham, Gemini, Sloan Digital Sky Survey

A new Milky Way-sized galaxy has been found nearby in the Coma Berenices constellation –; but this galaxy is more than meets the eye, astronomers say。 Though the diffuse blob is big enough in size and mass, the galaxy holds very few stars。 It should have been ripped apart millions of years ago in these conditions, but some mysterious force is holding it together。 It didn’;t take too long for scientists to discover what it was。

Using the W。M。 Keck Observatory and the Gemini North telescope, both stationed in Hawaii, the international team of researchers measured the velocities of the stars harbored by the Dragonfly 44 galaxy。 These velocities are used to calculate the mass of galaxies。

“;Amazingly, the stars move at velocities that are far greater than expected for such a dim galaxy。 It means that Dragonfly 44 has a huge amount of unseen mass,”; said co-author Roberto Abraham of the University of Toronto。

Collage of six cluster collisions with dark matter maps。 Image by NASA。

Judging from the data, it seems Dragonfly 44’;s mass is around 1 trillion times the mass of the sun or very similar to that of the Milky Way。 Unlike our own galaxy, however, less than one percent of Dragonfly 44’;s mass is made of stars or what astronomers call “;normal”; matter。 The rest of the 99。99 percent has to be dark matter —; an elusive form of matter that can’;t be directly seen, not with our current means at least, but whose influence can be felt。

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