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Abundance Analyses in B-type Stars with FASTWIND

Solving the "oxygen problem" for t Sco using FASTWIND code with spectral analysis and comparison methods to ensure accurate abundance data in early B-type stars. Results consistent with nebular constraints.

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Abundance Analyses in B-type Stars with FASTWIND

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  1. Abundance analyses in early B-type stars with FASTWIND The solution to the “oxygen problem”

  2. Target: t Sco (B0.2V, vsini ~ 13 km/s) • Spectral window: 4000 – 5000 A • SNR ~ 250 – 300 • Code: FASTWIND 8.5 + temperature correction • Model atoms: A10HHeO23-3, A10HHeO23+op • Methodology: Curve of growth method

  3. Comparing directly both results for a microturbulence of 5 km/s

  4. 34 4189 25 20 22 19 17 4943 4924 4075 16 14 13 12 10 4414 Grotrian diagram for OII 4317 4649 7 6 3 2 1

  5. The first 10 energy levels were changed for being consistent with the OP data The difference is not very large ... ... but produces inconsistencies inside the OII model atom

  6. L1 - L2 l(BB)l (OP) Dl 1 - 6 539.36 530.55 8.81 2 - 7 616.55 609.18 7.373 - 7 672.00 668.58 3.42 1 - 19 432.09 428.35 3.751 - 20 430.08 426.37 3.711 - 22 429.65 425.94 3.71 6 - 10 4652.78 4719.18 -66.406 - 12 4342.47 4550.84 -208.37 7 - 13 4419.26 4643.04 -223.7710 - 19 4075.90 4204.78 -128.88 14 - 20 4914.31 4914.31 0.00

  7. Once the problem is solved, the solution derived through FASTWIND is very consistent ... ... and in agreement with nebular abundance HD37020 (B0.5V in Orion nebula)

  8. Is it reasonable to use the microturbulence derived from the SiIII 4554 triplet ? There is a difference of ~ 0.17 dex Or it could be even larger !!!! ( ~ 0.4 dex)

  9. NU Ori (B0V, Teff = 30000 K, logg = 4.1) Checking the emergent fluxes predicted by the stellar atmosphere codes (FASTWIND, WMBASIC, CMFGEN, & TLUSTY) using nebular constraints Nebular geometry very important !!! M43, an apparently spherical HII region Simón-Díaz et al. (in prep.) Stellar abundance analyses in the Orion nebula (M42) Simón-Díaz et al. (submitted) HD37020 30000 K 4.0 dex 8.65 + 0.10 HD37023 32000 K 4.2 dex 8.59 + 0.10 HD37042 29000 K 4.2 dex 8.64 + 0.10 t Sco 32000 K 4.2 dex 8.70 + 0.10 Nebular gas: 8.65 + 0.03 Excellent agreement !! (Esteban et al. 2004)

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