Hi All,
I am looking on some biblio information about beta Cep. In particulary I would like to understand better the peak at 6677,.. Angstroms. What is ? I have seen that this peak is in some spectra on Bess Data base. I have also made a spectra and found the same peak (see image below). Sorry for the silly question but I searched in internet and I did not find information about that peak but I learned that this star is a variable probably a system of three stars.
Thanks ,
marco
Alfirk - beta Cep
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Alfirk - beta Cep
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Re: Alfirk - beta Cep
Marco,
This is probably He I at 6678.
What is the resolving power of your spectrograph? You should try to monitor beta Cep during a complete night and see if you can spot the Radial Velocity changes of Halpha and He I lines due to the pulsations of the star...
Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
This is probably He I at 6678.
What is the resolving power of your spectrograph? You should try to monitor beta Cep during a complete night and see if you can spot the Radial Velocity changes of Halpha and He I lines due to the pulsations of the star...
Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
Olivier Thizy
https://observatoire-belle-etoile.blogspot.fr/
https://observatoire-belle-etoile.blogspot.fr/
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Re: Alfirk - beta Cep
Olivier,
thanks for your prompt answer ! The resolving power of my spectrograph is 3000 at neon abs. line 6532.88 Angstroms.
In BeSS data base I have seen some of your spectras made the same night at different hour and minute. Please could you suggest me an interval time between the different spectra: for example one each hour or one each 30' ...
Why this star is in BeSS database ? I think is not a Be star with emission at H alpha....does not it ? Or the definition of Be star is wider than what I think ?
Thanks,
Marco
thanks for your prompt answer ! The resolving power of my spectrograph is 3000 at neon abs. line 6532.88 Angstroms.
In BeSS data base I have seen some of your spectras made the same night at different hour and minute. Please could you suggest me an interval time between the different spectra: for example one each hour or one each 30' ...
Why this star is in BeSS database ? I think is not a Be star with emission at H alpha....does not it ? Or the definition of Be star is wider than what I think ?
Thanks,
Marco
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- Location: Montpellier
- Contact:
Re: Alfirk - beta Cep
Hello Marco,
never too late for answer.
H alpha was seen in emisison before 2004 http://arasbeam.free.fr/spip.php?page=b ... 0&from=100
To be a Be star, the star of O B A spectral type, needs to be a subgiant or dwarf star, meaning luminosity class V-III, that show emission line in the Balmer lines. Even if it was once. So it is !
That for classical Be. Among nonclassical Be stars there are supergiant Be stars, peculiar Be stars, and Herbig Be/Ae stars.
Note that Bess concern also Herbig Be/Ae that are proto early spectral type stars.
Be peculiar stars, B[e], are different from classical Be due to their IR excess and the appearance of forbidden lines. It is a heterogeneous group, concerning proto planetary nebula, symbiotic B[e] stars, supergiants stars, pre main sequence stars and a lot are still unclassified. Look at the attempt to form a new group calling FS cma in this forum in campaign section. A very exiting subject.
Supergiant Be are from three type: Luminous blue variable stars (eta car, P cyg...), supergiant B[e] (MWC 349, MWC 314...) and Hubble-Sandage stars (AF And...).
So considering your resolution, R3000 and so the the ability to go deep in magnitude, it is interesting to observe weak classical Be stars, Herbig Be/Ae stars and FS cma group instead of bright Be well covered by high resolution spectroscopy.
never too late for answer.
H alpha was seen in emisison before 2004 http://arasbeam.free.fr/spip.php?page=b ... 0&from=100
To be a Be star, the star of O B A spectral type, needs to be a subgiant or dwarf star, meaning luminosity class V-III, that show emission line in the Balmer lines. Even if it was once. So it is !
That for classical Be. Among nonclassical Be stars there are supergiant Be stars, peculiar Be stars, and Herbig Be/Ae stars.
Note that Bess concern also Herbig Be/Ae that are proto early spectral type stars.
Be peculiar stars, B[e], are different from classical Be due to their IR excess and the appearance of forbidden lines. It is a heterogeneous group, concerning proto planetary nebula, symbiotic B[e] stars, supergiants stars, pre main sequence stars and a lot are still unclassified. Look at the attempt to form a new group calling FS cma in this forum in campaign section. A very exiting subject.
Supergiant Be are from three type: Luminous blue variable stars (eta car, P cyg...), supergiant B[e] (MWC 349, MWC 314...) and Hubble-Sandage stars (AF And...).
So considering your resolution, R3000 and so the the ability to go deep in magnitude, it is interesting to observe weak classical Be stars, Herbig Be/Ae stars and FS cma group instead of bright Be well covered by high resolution spectroscopy.