Spectral analysis of B-type stars in the
Gaia-ESO Survey
Morel, T., Semaan, T., Gosset, E., Zorec, J., Frémat, Y., Blomme, R.,
Lobel, A., and the WG13 team
The Gaia-ESO Survey
Public ESO Spectroscopic Survey (PIs: Sofia Randich & Gerry Gilmore)
Collaboration involving more than 400 scientists from almost 100 institutes
19 working groups
More than 30 papers accepted in refereed journals
35 observing runs completed with FLAMES-GIRAFFE and UVES (197/300 nights)
3 main target categories: field, clusters (28 OCs observed so far), calibrators
The Gaia-ESO Survey – WG13
Analysis of OBA stars
Currently 6 institutes (‘nodes’) involved in spectral analysis
For more details, see Ronny Blomme’s poster
The results presented in the following are only those obtained
by the Liège node for B stars
NGC 3293 and Trumpler 14
Young open clusters in Carina Nebula
Age: ~15 Myrs (NGC 3293) and ~2 Myrs (Tr 14)
Located at ~2.5 kpc
RG ~ 7.7 kpc
NGC 3293 observed by the “VLT-FLAMES Survey of
Massive Stars” (Evans et al. 2005, Hunter et al. 2009)
This study
Number of stars analysed: 95 in NGC 3293 and 40
in Trumpler 14
B0-B9
HR03, HR05A, HR06, HR14A
Spectral synthesis
He, N, O, Ne, Mg, Si
© AAT
Liège node analysis
Manual renormalisation of all spectra
Default
Renormalised
Liège node analysis
Manual renormalisation of all spectra
Default
Renormalised
Two-step approach:
Stellar parameters (Teff, logg, vsini, ξ, Vr) from global fitting of spectrum with a grid of
non-LTE TLUSTY synthetic spectra (solar chemical composition assumed)
Liège node analysis
Observations
Best fit
Liège node analysis
Manual renormalisation of all spectra
Default
Renormalised
Two-step approach:
Stellar parameters (Teff, logg, vsini, ξ, Vr) from global fitting of spectrum with a grid of
non-LTE TLUSTY synthetic spectra (solar chemical composition assumed)
Chemical abundances from spectral synthesis of selected wavelength regions. Performed
with Kurucz models and non-LTE line-formation code DETAIL/SURFACE
Liège node analysis
Region excluded
○
○
○ □ □ DIB
□ □
Observations
Best fit
○
○
□
□
□
□
□ O II
○ N II
□
Liège node analysis
Manual renormalisation of all spectra
Default
Renormalised
Two-step approach:
Stellar parameters (Teff, logg, vsini, ξ, Vr) from global fitting of spectrum with a grid of
non-LTE TLUSTY synthetic spectra (solar chemical composition assumed)
Chemical abundances from spectral synthesis of selected wavelength regions. Performed
with Kurucz models and non-LTE line-formation code DETAIL/SURFACE
Analysis not automated
Liège node analysis
Manual renormalisation of all spectra
Default
Renormalised
Two-step approach:
Stellar parameters (Teff, logg, vsini, ξ, Vr) from global fitting of spectrum with a grid of
non-LTE TLUSTY synthetic spectra (solar chemical composition assumed)
Chemical abundances from spectral synthesis of selected wavelength regions. Performed
with Kurucz models and non-LTE line-formation code DETAIL/SURFACE
Analysis not automated
SB2 and Be stars discarded
Comparison atmospheric parameters NGC 3293 with
those from ‘VLT-FLAMES Survey of Massive Stars’
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Abundance results
● Apparently single star in NGC 3293
○ Binary (?) in NGC 3293
- - - - - - Asplund et al. (2009)
Mean value of VLT-FLAMES
Survey (± 1σ)
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Abundance results
● Apparently single star in NGC 3293
○ Binary (?) in NGC 3293
- - - - - - Asplund et al. (2009)
Mean value of VLT-FLAMES
Survey (± 1σ)
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Abundance results
● Apparently single star in NGC 3293
○ Binary (?) in NGC 3293
- - - - - - Asplund et al. (2009)
Mean value of VLT-FLAMES
Survey (± 1σ)
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Abundance results
● Apparently single star in NGC 3293
○ Binary (?) in NGC 3293
- - - - - - Asplund et al. (2009)
Mean value of VLT-FLAMES
Survey (± 1σ)
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Abundance results
NGC 3293
Trumpler 14
● Apparently single
○ Binary?
- - - - - - Asplund et al. (2009)
Homogeneous
nitrogen abundances
Summary NGC 3293 abundances
This study
Summary NGC 3293 abundances
This study
VLT-FLAMES Survey
Summary NGC 3293 abundances
This study
VLT-FLAMES Survey
Asplund et al. (2009)
NGC 3293 vs Trumpler 14 abundances
NGC 3293
NGC 3293 vs Trumpler 14 abundances
NGC 3293
Trumpler 14
NGC 3293 vs Trumpler 14 abundances
NGC 3293
Trumpler 14
Asplund et al. (2009)
NGC 3293 vs Trumpler 14 abundances
Star-to-star scatter comparable to
uncertainties: chemical homogeneity
Conclusions and future work
One of the first homogeneous chemical analyses of an ensemble of stars from B9 up to B0
and with a wide range of vsini values
No dependence between chemical abundances and stellar parameters
Quite surprising lack of chemically-peculiar stars (especially amongst late B-type stars)
No clear evidence for any N-rich stars
Abundances in NGC 3293 consistent with those reported by ‘VLT-FLAMES Survey of
Massive Stars’
Mean abundances in NGC 3293 and Trumpler 14 consistent within the errors
Conclusions and future work
One of the first homogeneous chemical analyses of an ensemble of stars from B9 up to B0
and with a wide range of vsini values
No dependence between chemical abundances and stellar parameters
Quite surprising lack of chemically-peculiar stars (especially amongst late B-type stars)
No clear evidence for any N-rich stars
Abundances in NGC 3293 consistent with those reported by ‘VLT-FLAMES Survey of
Massive Stars’
Mean abundances in NGC 3293 and Trumpler 14 consistent within the errors
Still to be done:
Effect of gravity darkening for fast rotators
Benchmarking on stars observed by GES
Computation of uncertainties
Analysis of UVES spectra (additional chemical elements)
Conclusions and future work
One of the first homogeneous chemical analyses of an ensemble of stars from B9 up to B0
and with a wide range of vsini values
No dependence between chemical abundances and stellar parameters
Quite surprising lack of chemically-peculiar stars (especially amongst late B-type stars)
No clear evidence for any N-rich stars
Abundances in NGC 3293 consistent with those reported by ‘VLT-FLAMES Survey of
Massive Stars’
Mean abundances in NGC 3293 and Trumpler 14 consistent within the errors
Still to be done:
Effect of gravity darkening for fast rotators
Benchmarking on stars observed by GES
Computation of uncertainties
Analysis of UVES spectra (additional chemical elements)
Science issues to tackle:
Constraints on cluster ages
Abundance patterns (He, N, O) compared to predictions of evolutionary models