C2 Swan System ?

[Lars Zielke]

Hi

In preparation for new targets, I have passed a few articles that have reference like "C2 Swan System (0,0) band in emission, C2 Swan system (1,0) band head"

I'm having trouble finding information about the "C2 Swan System" - can anyone help?

Cheers
Lars

[Francois Teyssier]

Hi Lars,

You can find a few spectra of carbon stars on : http://www.astronomie-amateur.fr/Projet ... 0hb.html#C
with a short summary of the classification (combinaison of température and carbon concentration)




Two readings :

Spectroscopic atlas of crabon stars : Barnbaum, 1996 : http://adsabs.harvard.edu/abs/1996ApJS..105..419B
Catalog of Carbon stars : Alksnis and al., 2001 : http://adsabs.harvard.edu/abs/2001BaltA..10....1A

is that answer your question ?

Cheers

François

[Lars Zielke]

Hi François

I certainly helped me, thanks a lot. I'll try to clarify below...

I'm still a little confused though, because in this context it's not about carbon star types, but a comment about the spectre of R CrB at the 2003 light minimum.

Here a link to one of the papers I've reading
http://articles.adsabs.harvard.edu/cgi- ... lassic=YES

From what I understand the C2 emissions (Swan systems) is coming from the carbon clouds around the star or? So the reference to the Swan system tells me something about the temperature and amount/density of carbon in this cloud?



This is of interest since TYC 2505-672-1 appears to be a R CrB. Been trying very hard to get a spectrum with SA, but no luck so far. It's very dim. Maybe the new ALPY could do it or I'll have to wait until it rises in brightness again.?

I've done photometrics on the star, right ow it's at v-mag 15.3

[Francois Teyssier]

Hello Lars,
Intesting target, but quiet challenging, even with a Lisa or the next Alpy

Did you see recent Atel : http://www.astronomerstelegram.org/?read=4834

Christian produce a list of R CrB stars :
http://www.astrosurf.com/buil/us/peculiar2/rcrb.htm
and a spectrum of R CrB
R CrB is currently at mag 11, almost easy


Bonne continuation,
François

[Lars Zielke]

Hello François

I did see Atel 4834. What is intriguing is that it doesn't show any carbon. I thought carbon dust condensation was the reason for such fading?

From the telegram:
The object's behavior is unusual for the typical R CrB stars. This may be the first active episode of the red giant entering the short RCB phase. That may explain the absence of surrounding carbon dust, small J-K colors and presence of hydrogen emission.

I have no idea what they mean about the "absence of carbon", so I sent some mails to the team hoping to get some answers. Does anyone here know what they mean?

I can't get a spectre from it now, to faint, but I hope I can get it when it's rising again.

Cheers
Lars

[Lars Zielke]

A translation of a presentation the MASTER team showed Feb. 15. can be found here over the next couple of days. Rather interesting.

http://www.nightsky.dk/Astronomi/Variab ... -672-1.pdf

From here (source)
http://master.sai.msu.ru/en/osa/

[Francois Teyssier]

A review about R CrB stars
Some explanations about C2 bands

http://adsbit.harvard.edu/cgi-bin/nph-i ... .108..225C

Best regards

François