Quote:
Originally Posted by xelasnave
Wow just like being there.
Wonderful.
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Quote:
Originally Posted by Placidus
Thanks for the explanation Steve, and for the superb photo. I can see that some of the really bright favourites is a place to explore SII and NII.
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Thanks for the comments on the image.
Quote:
Originally Posted by Merlin66
Mike,
As Steven has said, the heavier "metals" need more energy to ionise...
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Hi Ken.
Heavier metals require more energy to overcome the Coulomb barrier for fusion of the parent nuclei. Ionization is the removal of electrons from atoms.
Quote:
Originally Posted by Placidus
Ken,
I should like to know whether the morphological distributions of SII and NII relative to the others tells us anything extra, and if so, what.
I have read Kaler, and believe that I understand him. But he does not specifically address my questions: what kinds of objects are especially rich in SII or NII? What does that tell us? Name some objects?
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Interestingly while the Ha and NII emission lines overlap in wider band Ha filters (Ha=656.3 and NII doublet 653.8 and 658.4), 3nm NII filters are used to enhance detail in certain planetary nebulae and Wolf Rayet bubbles when compared to Ha images.
The extreme outer extremities of the Dumbbell nebula show up better in NII as shown in the attachment.
Regards
Steven