Canopus with 300D

[theodog]

Hi All,
Took this tonight before the clouds and rail rolled in agaaaiiin.
Canopus 2sec exp. with un moded 300D.
300l/mm HM 'StarAnalyser'
HM Adjustable slit/mask
Through 150mm Mak
I see lines:D
Anybody prepared to guess which ones?
:)

[telecasterguru]

I don't have much knowledge in this area of astronomy but what would you require to analyze this?
Would you use some type of spectrum analyzer? Would this give some clues as to the make up or properties of the star?
I am going to have to do some research into this. Any ideas where to start?

Thanks

Frank

[Dennis]

I can see Hydrogen, Helium, Lithium, Beryllium, Carbon, Nitrogen, Oxygen, Magnesium, Mercury, Sodium, Calcium, Iron and a few other Fraunhofer Lines!:whistle:;):thumbsup:

Cheers

Dennis

[robin_astro]

Hi Jeff,

I hope you don't mind a Pom who has never even seen Canopus :D joining in but I think I can make a stab at it.

With a spectral type of F0i, Canopus is a supergiant at the hot end of the F class and so shows hydrogen Balmer lines like the A type stars. It also shows metallic lines like the G and K stars. The sodium D doublet (5890/5896) should be particularly clear. Sooooo.......

I think the narrow line in the Yellow is Sodium (not the broad line, that is an artifact caused by the gap between the green and red channels) The rightmost prominent line in the blue is probably H beta (4861) On that basis I had a go using vspec to produce the attached graph from your image and compared it with a F0i type star from the VSpec (pickles) library. The dispersion works out at about 8A/pixel. Armed with this calibration is is probably possible to identify the other Balmer lines and Fe and Mg are probably in there too.

Here is another spectrum of an F supergiant (Epsilon Aurigae) taken with the Star Analyser 100 in front a telephoto lens on a 350D.
http://www.threehillsobservatory.co.uk/astro/spectroscopy_11.htm

Best Wishes
Robin
www.threehillsobservatory.co.uk (http://www.threehillsobservatory.co.uk)

[theodog]

Thanks Dennis, there has to be one of those elements there somewhere.:lol:

Hi Robin, welcome over to IIS.:welcome:
I see the hand of experience there. Thanks for the result.
I had three parts to my investigation,
What is the size of spec I could fit onto the 300D?
What would the spec look like through the tri-colour image in the 300D?
And How would the adjustable slit work?
I was happy with the results from 1 & 3, 2 was woefull (I sort of expected that).
Could you upload the .dat file for your VSpec graph as a .zip?
Could I use your www to demonstrate in my High School Physics class?
Thanks for your help.
:thumbsup::D

[robin_astro]

Hi Jeff,

The .dat files are attached. I must admit I am not 100% happy with the calibration. If it is right then there must be some non linearity as the zero order did not end up very close to zero Angstroms. I used a linear calibration to the two lines which works fine with the small dispersion angles of a 100 line grating but might not work so well with a 300l/mm grating) Also on this basis the response at the red end seems to extend further than I would expect for an unmodded camera (My 350D runs out just beyond H alpha at 6563)
The stronger H Balmer lines of an A star would probably be better to nail the calibration. Vega is well placed here ATM but of course that is no good for you :rolleyes:

There's no problem using the stuff on the website in school :)

Cheers
Robin