M46/M47
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M46/M47 |
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Deep Sky Object Chart
| Stars in Canis Major
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M46/M47 are two bright star clusters, properly in the neighboring constellation of Puppis but mentioned here for their easy location by referring to the pattern of Canis Major. The clusters are very different in appearance, although similar in overall brightness; M46 has 150 fairly faint stars, and M47 has half as many but brighter stars. The apparent closeness of the clusters is an illusion; M46 is perhaps 4700 light years away, and we see M47 in the foreground, just 1500 light years from us. This suggests there is no real tie in the brightness contest - M46 would blow the doors off M47 if the distances were similar. | |||||||||
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While both clusters can be glimpsed by the unaided eye under good conditions, and are wonderful in telescopes, larger instruments reveal something extra - the "planetary" nebula NGC 2438, a softly glowing sphere of gas near the center of M46. Actual membership in the cluster is controversial - it may just happen to be in the area, with the cluster passing through. NGC 2438 is magnitude 11, and a bit larger than Jupiter appears (65 arc seconds). This is a challenging target for moderate amateur telescopes (~ 8 inches aperture) and is often overlooked.
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