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Wavelength connfusion - Any help welcome


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Hey all,

I understand that narrowband emission filters only let in a tiny amount of the specific light caused by an element in say a nebula.

Say you were looking at a planetary nebula and you put it through 3 filters for nitrogen, hydrogen and oxygen. The nebula would come out nicely right after you had combined the images.

But can you do the same to find out the composition for their main star in the middle? Or this something different involved because they are a star?

Thanks,

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Thanks for that Olly, I am studying it closely...

But from what I can gather, and emissions cloud is way to cold compared to it's central star so you couldn't apply narrowband filters to work out its composition, that its done with spectrography which is completely different!?!?

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The comparison bandwidths are not sufficient to do that sort of work.

Certainly with a spectroscope, where you can analyse various gaseous contents, temperatures and quantites as well as doppler movements, all things are possible.

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Thanks guys very helpful, so the wavelengths studying stars and nebula are very different.

Would it be possible to work out a white dwarfs composition from the material viewed around it in a planetary nebula that had previously been dispersed?

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  • 2 weeks later...

Stars generally have just thr raw elements in them, nebula can have moleclues of assorted, usually simple compounds in the.

Orion has been found to have the folowing: water (H2O), carbon monoxide (CO), formaldehyde (CH2O), methanol (CH3OH), dimethyl ether (CH3OCH3), hydrogen cyanide (HCN), sulphur oxide (SO) and sulphur dioxide (SO2).

Carbon stars have been found to have simple compounds as part of them, they are cool stars and so compounds can exist in their outer layers.

The nebula remains of a star going to a white dwarf will indicate some of what was thrown off. But you will have to look at stellar evolution to determine if the bit thrown off is typical of the majority of the star that went nova. Since fusion stops at iron and you don't see much iron in the clouds I would say that the layers thrown off may not be typical of what the star was composed of before it went bang.

A white dwarf going supernova does I think result in everything being thrown out, but the mechanism is different.

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Thanks guys very helpful, so the wavelengths studying stars and nebula are very different.

Would it be possible to work out a white dwarfs composition from the material viewed around it in a planetary nebula that had previously been dispersed?

As has been said, stars are generally far too hot for compounds to form. In fact even atoms are rare, as most of the stuff is ionized.

Once the material is thrown off, its in a different environment, and you do get chemical reactions happening - there is a whole disciple - astrochemisty - that investigates this.

Another issue is that while all atoms have spectra, not all molecules do, it needs generally different atom compounds to be detected, So things like CO, CO2 etc can be, but not O2 N2 etc.

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