Quote:
Originally Posted by Placidus
Here is the Crab Nebula, taken under dodgy conditions, and nowhere near enough exposure.
Question: We've read that the blue glow of the Crab is Cerenkov radiation - electrons spiralling in a powerful magnetic field. Presumably only some proportion of that would go through our 3nM OIII filter. Would we in fact do better with a wideband blue filter? Ordinarily we'd just give it a try, and all would be revealed, but what with Christmas, Cloud, and Crispy Electronics, it's been a struggle.
|
Hello Mike and Trish,
The correct terminology is synchrotron radiation.
Cherenkov radiation occurs when gamma ray photons from the Crab are converted into high velocity electron/positron showers when interacting with atoms and molecules in our atmosphere.
These showers which carry a charge can further interact with atoms and molecules causing then to be polarized by the shower.
As the shower passes, the atoms and molecules return to their non polarized state and produce Cherenkov radiation in the process.
Our atmosphere is the source for Cherenkov radiation not the Crab.
Since synchrotron radiation is basically a continuous spectrum you will do better with a wideband blue filter.
Synchrotron radiation is highly polarized and using a polarisation filter at different angles combined with luminance data, leads to some very interesting details not ordinarily seen as revealed in the attachment.
There are not too many amateur images of a polarized Crab and it might make an interesting challenge.
Regards
Steven