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F ast A nalysis of St ellar Atmospheres with Wind s

FastWind is a fast code for analyzing OBA stars' optical and IR spectroscopy, independent of wind strength and luminosity class. Developed by E. Santolaya-Rey and team, it includes features like line-broadening, line-blocking, and clumping effects for accurate results.

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F ast A nalysis of St ellar Atmospheres with Wind s

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  1. FastWind Fast Analysis of Stellar Atmospheres with Winds developed and permanently improved by E. Santolaya-Rey1, M. Urbaneja1, R. Venero2, A. Jokuthy3, A. Herrero1 and J. Puls3 1 Instituto de Astrofisica de Canarias (IAC) 2 Observatorio Astronómico, La Plata 3 Universitätssternwarte München FLAMES meeting Amsterdam

  2. The goal … optical and IR spectroscopy for OBA stars with Teff  8,500 K independent of luminosity class and wind strength fast code, since large parameter space to be investigated if wind contribution significant FLAMES meeting Amsterdam

  3. The code … FastWind • basic code by Santolaya-Rey et al. 1997, A&A 323 + improvements • features of present release • atomic data driven (“DETAIL input”) • unified atmosphere (smooth transition from pseudo-hydrostatic photosphere to wind) • CMF transfer incl. line-overlap for ionic species aimed at being analyzed • line-broadening (Stark, pressure-…) included in line formation • “background” (i.e., non-DETAIL) elements in approximate NLTE (improved Abbott-Lucy approach, • ALI-like coupling of approximate rate-equations with radiation field) • approximate line-blocking (using suitable means) • flux-conservative, i.e., line-blanketing included • very fast (30 minutes per model on PC) • suited for thick and thin winds • tested by comparison with • DETAIL/SURFACE (Butler&Giddings), TLUSTY (Hubeny): very thin winds • CMFGEN (Hillier), WM-basic (Pauldrach): “normal” winds • Kurucz: A-dwarfs • so far, mostly applied for H/He-line formation in optical and IR • C/N/O/Si/Mg for B-star analysis recently installed FLAMES meeting Amsterdam

  4. … what has been done meanwhile (next release of FASTWIND) • consistent temperature in the outer wind (if one believes in radiative equilibrium …) • by means of electron thermal balance (advantageous compared to radiative equilibrium in those regions where radiation field is almost independent on Te (cf. Kubat et al. 1999, A&A 341) • important for IR-spectroscopy (present approach: define lower cut-off temperature Tmin) • in order to obtain consistent heating/cooling rates, occupation number of most important elements (light ions +a-elements + Fe/Ni) are calculated “almost” exactly (Sobolev) • agreement with WMbasic and Kurucz • clumping effects included • O-star winds seem to be clumped even in lower wind, leads to an overestimation of Mdot (Puls et al. 2002, proc. IAU Symp. 212) • important for dense winds + IR FLAMES meeting Amsterdam

  5. … and what still needs to be done • inclusion of “high” metal ions (e.g., NIV/NV) • important for (very) hot stars to define Teff (if HeI becomes too weak) • improvement of treatment of line-blocking • stochastic approach (following Wehrse et al. 1998, JQSRT 60), work in progress FLAMES meeting Amsterdam

  6. per He-abundance (typically 0.1, 0.15, 0.2) and back-ground metallicity (typically solar, 0.5 and 0.1 solar) at least 3-D grid required • equidistant in Teff, log g and log Q, with wind density parameter • if Q remains constant, spectrum and fluxes remain very similar, since • 2 dependent line-processes in the wind scale with Q • (recombination lines and resonance lines from ionization stages one below the major stage). • other processes scale with either • THUS: Q best compromise • typical values for log Q (Rstar in solar units, vinf in km/s, Mdot in Msun/yr) log Q = -14 ... –11.5 (thin -> very thick winds); maybe: use WLR • v , b (velocity law) in dependence of spectral type/ l.c. (i.e., Teff , log g and R) • Mdot from Q, v and R coarse analysis by model - grids FLAMES meeting Amsterdam

  7. Macroturbulence? • increasing evidence that supersonic macroturbulence present in many stars • mostly for B-supergiants, however also for a couple of dwarfs • have to understand physics • suggest to contact stellar modelling people FLAMES meeting Amsterdam

  8. O-supergiant, dense wind HeII ground-state departure coeff. HeIII/II/I ioniz. fractions O-dwarf, very weak wind HeI ground-state departure coeff. (singlet and triplet) TEST approximate NLTE fully-drawn: H/He-model, all levels in “exact” NLTE dotted: H-model + He in approximate NLTE Teff = 40,000 K log g = 3.7 (sg) = 4.0 (d) from Puls et al., in prep. for A&A FLAMES meeting Amsterdam

  9. Comparison of emergent fluxes with results from CMFGEN Cyg OB2 #7 (O3If*) fluxes without and with line-blocking/blanketing CMFGEN vs. FastWind from Herrero et al. 2002, A&A, in press FLAMES meeting Amsterdam

  10. magenta: WM-basic green: converged model, lines omitted black: FastWind Most important for optical H/He analysis: background at 303 Å(HeII Lya) HeI (504) and HeII(228) continua Comparison of emergent fluxes with results from WM-basic Here: dwarfs (D) and supergiants (S) at Teff = 35,000 and 45,000 K FLAMES meeting Amsterdam

  11. D45 D35 magenta: WM-basic green: “old” Te(r) with Tmin black: FastWind S45 S35 Comparison of temperature stratification with results from WM-basic Here: dwarfs (D) and supergiants (S) at Teff = 35,000 and 45,000 K FLAMES meeting Amsterdam

  12. Comparison of temperature stratification with Kurucz model Teff = 9,500 K log g = 4.0 “solar” abundances FLAMES meeting Amsterdam

  13. Analysis of Galactic O-type stars- some examples of fit quality: O2/3 stars Lines used for analysis Hydrogen: Balmer a ... e HeI singlets: 4387,4922 triplets: 4471, 4713 HeI/HeII: 4026(T), 6678(T), 6683(S) HeII n=3: 4686 n=4: 4200, 4541 n=5: 6406, 6527 HD93129A: O2If* Teff 50,500 -> 42,500 K (upper limit 45,000K) log g 3.95 -> 3.70 YHe 0.1 -> 0.1 HD93250: O3V((f)) Teff 50,500 -> 46,000 K log g 4.00 -> 3.95 YHe 0.1 -> 0.1 FLAMES meeting Amsterdam

  14. Analysis of Galactic O-type stars- some examples of fit quality: O9.5 stars a Cam: O9.5Ia Teff 30,000 -> 29,000 K log g 3.00 -> 2.97 YHe 0.2 -> 0.1 HD209975: O9.5Ib Teff 32,500 -> 32,000 K log g 3.20 -> 3.20 YHe 0.1 -> 0.1 Note: theoretical HeI4471 too weak -> so-called “generalized dilution effect” (Voels et al.1989, ApJ340, and ref. therein) FLAMES meeting Amsterdam

  15. Analysis of Galactic O-type dwarfs O3V((f)) O3V((f)) O3V((f)) O5V((f)) O7V n O9V Re-analysis of O-star sample from Puls et al. (1996) by means of FastWind (Repolust et al., A&A, accepted) FLAMES meeting Amsterdam

  16. Analysis of Galactic O-type supergiants O3If* O4I(f) O5If+ O6I(n) fp O7Ib(f) O7.5I(n)((f)) Re-analysis of O-star sample by Puls et al. (1996) by means of FastWind (Repolust et al., A&A, accepted) FLAMES meeting Amsterdam

  17. (B2Ia) Resolution 8000 - 8500 H-band approx. parameters Teff = 18,500 K log g = 2.1 YHe = 0.1 log Q= -13.1 (weak wind) Br11 HeI (triplet) Br10 K-band Observations by Hanson, Puls and Meynet Reduction by M. Hanson HeI (singlet) HeI (triplet) Brg + HeI VLT/ISAAC H/K-band spectroscopy FLAMES meeting Amsterdam

  18. Subaru IRCS near infrared spectroscopy Resolution 9000 Calibration Standard HD199629 (58 Cyg) A1Vn cross check of reduction and broadening functions Observations by Hanson, Kudritzki and Puls Reduction by M. Hanson FLAMES meeting Amsterdam

  19. B-supergiants (A-9: B1.5, B12: B0.5) in NGC300 (Sculptor group, d  2 Mpc) for comparison HD14956 (B1.5Ia) results: stellar + wind params + indiv. abundances A-9 : 0.3*solar B-12: solar with respect to sum of -elements O + Si + Mg Observations/reduction VLT/FORS Bresolin et al.2002, ApJ 567 Extragalactic abundance analysis by means of B-supergiants From Urbaneja et al. 2002, A&A Letters, submitted FLAMES meeting Amsterdam

  20. Alpha Cam with different Mdot, however same Q 2nd model has lower density! FLAMES meeting Amsterdam

  21. dashed: calibration by Vacca et al.,1996, ApJ 460, l.c.V (upper) and l.c. I (lower) objects enclosed by circles: (very) fast rotators with v sin i  300 km/s binary! HD93129A Spectral type – Teff relation re-analysis of Galactic O-star sample from Puls et al, 1996 (24 objects, lc. I, III, V) by means of FastWind, using optical H/He lines From Puls et al.2002, proc. IAU Symp. 212, in press FLAMES meeting Amsterdam

  22. binary! Comparison with results from other investigations objects enclosed by circles: (very) fast rotators with v sin i  300 km/s HD93129A • Pup consistent with Crowther et al. FLAMES meeting Amsterdam

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