AAS 197, January 2001
Session 78. Nearby Galaxies I
Display, Wednesday, January 10, 2001, 9:30am-7:00pm, Exhibit Hall

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[78.10] NLTE Model Atmosphere Analysis of Main-Sequence O Stars in NGC 346

J.-C. Bouret, S. R. Heap (NASA's GSFC), I. Hubeny (AURA, GSFC), T. Lanz (U. Maryland, GSFC), D. J. Hillier (U. Pittsburgh), D. J. Lennon (IAC), L. J. Smith, C. J. Evans (UCL)

To serve as spectral templates of young, low-metallicity populations, high-resolution, high-quality, ultraviolet (STIS) and optical spectra of several main-sequence O stars in NGC 346 have been obtained. Stellar parameters and abundance of light elements are derived from the optical spectrum using NLTE, line-blanketed, photospheric models calculated with TLUSTY. In addition, the UV spectrum is analyzed with the NLTE, line-blanketed wind model code, CMFGEN, to derive wind parameters (mass-loss rate, clumping properties, terminal velocity). Iron abundances, derived from fitting \ion{Fe}{4} and \ion{Fe}{5} lines with the two NLTE codes, compare favorably. We achieve good matches of the observed spectra, thus supporting our modeling work of spectra of starburst galaxies at high redshift. We finally discuss the dependence of the mass-loss rate in terms of metallicity and luminosity. This work was supported through a NASA/NRC RA award and STScI grants (GO 7437, AR 7985).

The author(s) of this abstract have provided an email address for comments about the abstract: bouret@winds.gsfc.nasa.gov

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