Dissolve from Optical to X-ray Image of Westerlund 1
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This sequence begins with an optical view of the star cluster, known as Westerlund 1. When the view dissolves into Chandra's X-ray image, the unusual neutron star -- a dense whirling ball of neutrons about 12 miles in diameter -- appears very brightly.
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(Credit: Optical: ESO/WFI/2.2-m MPG; X-ray: NASA/CXC/UCLA/M.Muno et al.)