AG Dra

[Tony Rodda]

I’ve begun submitting spectra to the BAA and BeSS websites but really liked the look of the symbiotic star spectra captured by David Boyd for the ARAS Eruptive stars team.  Some fascinating objects with very different spectra.

Heartened by the fact that my spectrum looked in line with David’s I submitted this…

My first submission accepted by ARAS today.

PS. Anyone know what the emission feature is around the 681/2 nm mark?

Attachments:

1. 

   AG-Dra-Lines.png
   

[David Boyd]

Hi Tony,

That is the broad Raman scattered O VI line at 6825A. See http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1989A%26A…211L..31S&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

It was a mystery for a long time until Schmid published his paper. It’s a trademark of symbiotic stars with high excitation nebulae.

David

[Tony Rodda]

David (et al),

The apparent ‘lack’ of a photospheric spectrum and a dual component means ‘what’ in terms of how we measure a symbiotic star?

Using another M3 standard star got the correct result for AG Dra.  Is that assumption correct?  That is, use the spectral response for the more luminous component?

Regards

T

[David Boyd]

Hi Tony,

I’m not sure I understand your question. Measuring the instrumental and atmospheric response for a symbiotic is no different to any other star in that you want to use a reference star close in altitude and azimuth to the target and for which you have a good spectrum, so ideally a Miles library star but failing that a Pickles spectrum for the same spectral type as the reference star. It doesn’t need to have a spectral type similar to your target star. That should enable you to correct your measured spectrum to the exo-atmospheric spectrum of the target, whatever type of star it is.

Apologies if I’ve misunderstood what you were asking. If so, try again!

David

[Tony Rodda]

Hi David, thanks (once again) for your responses.

I was making life difficult for myself in the belief that I needed a reference star close in proximity AND in spectrum to the intended target.  (Indeed I’d noticed a better fit when I did that). 

I’ll relax that spectrum requirement (and the time it takes to find a suitable ref star!).  

(That does indeed solve the issue of ‘what ref star do I choose for a binary of differing spectral components?’.  Doh!).

It looks like being fine up here tonight so I’ll chase a few more Be and ARAS symbiotics. I received a good response and a few ‘pointers’ from Francios T on submission of my first spectrum to him and I’m keen to try a few more.

Regards

T

[David Boyd]

Hi Tony,

Did you see the recent posts on the ARAS Forum about professional interest in the symbiotics SU Lyn and AG Dra? Consider adding these to your target list.

Cheers, David

[Tony Rodda]

Thanks David. Will do. 

Rgds

T

[Gary Poyner]

Readers of these AG Dra pages might be interested in this pro-am campaign which has just been announced…

http://www.britastro.org/vss/aavso_alert_notice_572.htm

Although not specifically aimed at spectroscopy, you might find it of interest.

Gary

[Tony Rodda]

Rgds

T

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