Spectrum of the Ring Nebula

Using SharpCap for other Astro Imaging such as all sky cameras and meteor detection
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oopfan
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Spectrum of the Ring Nebula

Post by oopfan »

An interesting NASA APOD today:
https://apod.nasa.gov/apod/ap210721.html

The identity of the three rings:
Left side: Ha + NII
Middle: OIII
Right side: Normal visual appearance

OIII is very strong in Planetary Nebulae, even stronger than Ha in many cases. However, OIII tends to be weak in regular Emission Nebulae.

Brian
timh
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Re: Spectrum of the Ring Nebula

Post by timh »

Interesting picture Brian. I have noticed that you can buy a diffraction grating eyepiece

https://www.rspec-astro.com/star-analyser/

and have wondered how well it would perform in practice. Could be interesting comparing carbon stars with types O and A etc?

Tim
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Re: Spectrum of the Ring Nebula

Post by oopfan »

Hi Tim,

Centuries ago when I was a teenager, I built a spectrograph for my telescope using a grating and some simple optics. My first subject was Vega. The Ha absorption band was very broad. It indicates that the atoms are super-heated, and bouncing around at high velocity, some moving towards us and others away from us. When they emit photons after absorption, there is a massive red shift and blue shift, therefore the broad absorption band. I would imagine that the absorption lines of Carbon stars are narrower, but you will pick up the heavier elements.

It's been a while since I visited the Rspec website, but I think their software can identify the spectral type of a star from its spectrum.

Brian
timh
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Re: Spectrum of the Ring Nebula

Post by timh »

Hi Brian,

That was a good project for a lad..unfortunately as a teenager my hobby was chemistry and I used to make explosives - until a short stay in hospital cured me of that and I switched to amateur electronics and radio which was less destructive.

Your mention of Doppler line broadening led me to this

http://www-star.st-and.ac.uk/~kw25/teac ... widths.pdf


Most of of the broadening probably is collisional at high temperatures in stars ...I guess that the emission lines from relatively cool and low density emission nebulae are much narrower then than the corresponding absorption lines in stellar atmospheres?

Tim
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oopfan
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Re: Spectrum of the Ring Nebula

Post by oopfan »

Tim,

Interesting. The red/blue shift was the explanation given in the 1970s, as best I can remember. Science does evolve!

Brian
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