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PGC 6240, also known as AM 0139-655 or the White Rose Galaxy, is a very large and old galaxy in the southern constellation of Hydrus, about 345 million light years away from Earth. Appearing like a white rose in the sky, the galaxy has foggy shells of stars that rotate around a luminous center with few shells lying close to it while others at a distance. Those distant from the center appear disconnected from the white rose. The 'White Rose' galaxy intrigues astronomers because the differing ages of its globular clusters; there are a population of relatively young globular clusters around 400 million years old, another group of older ones around 1 billion years old, and older ones still. The ages of the younger two align with the ages of the shells around the galaxy proper. This suggests that the younger clusters and shells formed in bouts of starburst star formation following the merger of the galaxy with another.〔 ==Notes and References== References Bibliography * * * 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「PGC 6240」の詳細全文を読む スポンサード リンク
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