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- Tue Dec 01, 2020 6:26 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Cygnus Without Stars (2020 Nov 30)
- Replies: 7
- Views: 2687
Re: APOD: Cygnus Without Stars (2020 Nov 30)
Beautiful picture. But I’m puzzled by this in the description : “Therefore, in this 18-hour exposure image, blue areas are hotter than red.” I realize that blue stars are hotter than red ones. And O III emission is blue and so higher energy than Red H II. But does this tell us anything about the tem...