The metallicity gradient of M 33: chemical abundances of H ii regions
نویسندگان
چکیده
منابع مشابه
Measuring Chemical Abundances in Extragalactic Metal-Rich H II Regions
The analysis of metal-rich H ii regions has a profound impact on the calibration of abundance diagnostics widely used to measure the chemical content of star-forming galaxies, both locally and at high redshift. I review the main difficulties that affect direct abundance determinations from temperature-sensitive collisionally excited lines, and briefly discuss strong-line methods, in particular ...
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Far-ultraviolet (900-1200Å) spectral synthesis of nine giant extragalactic H II regions in M33 and M101 is performed to study their massive stellar content. Several parameters are quantified, predicted, and compared to the literature: age, stellar mass, IMF slope, number of O-type and Wolf-Rayet stars, Hα and 5500Å continuum fluxes. The results of this particular technique are consistent with o...
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We have obtained multi-object spectroscopy of H II regions in the spiral galaxy M51 with the Keck I telescope and the Low Resolution Imaging Spectrometer. For ten objects we have detected the auroral line [N II]λ5755, while [S III]λ6312 has been measured in seven of these. This has allowed us to measure the electron temperature of the gas and to derive oxygen, sulfur and nitrogen abundances for...
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We calculate a grid of spherically symmetric OB stellar atmospheres at low metallicities, including both non-local thermodynamic equilibrium (NLTE) and metal line blanketing effects. This is done to assess the uncertainties in helium abundance determination by nebular codes due to input stellar atmosphere models. The more sophisticated stellar atmosphere models we use can differ from LTE models...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2007
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20077445