2012ApJ...747...15K -
Astrophys. J., 747, 15 (2012/March-1)
Quantitative spectroscopy of blue supergiant stars in the disk of M81: metallicity, metallicity gradient, and distance.
KUDRITZKI R.-P., URBANEJA M.A., GAZAK Z., BRESOLIN F., PRZYBILLA N., GIEREN W. and PIETRZYNSKI G.
Abstract (from CDS):
The quantitative spectral analysis of low-resolution (∼5 Å) Keck LRIS spectra of blue supergiants in the disk of the giant spiral galaxy M81 is used to determine stellar effective temperatures, gravities, metallicities, luminosities, interstellar reddening, and a new distance using the flux-weighted gravity-luminosity relationship. Substantial reddening and extinction are found with E(B - V) ranging between 0.13 and 0.38 mag and an average value of 0.26 mag. The distance modulus obtained after individual reddening corrections is 27.7±0.1 mag. The result is discussed with regard to recently measured tip of the red giant branch and Cepheid distances. The metallicities (based on elements such as iron, titanium, magnesium) are supersolar (~0.2 dex) in the inner disk (R ≲ 5 kpc) and slightly subsolar (~ - 0.05 dex) in the outer disk (R ≳ 10 kpc) with a shallow metallicity gradient of 0.034 dex/kpc. The comparison with published oxygen abundances of planetary nebulae and metallicities determined through fits of Hubble Space Telescope color-magnitude diagrams indicates a late metal enrichment and a flattening of the abundance gradient over the last 5 Gyr. This might be the result of gas infall from metal-rich satellite galaxies. Combining these M81 metallicities with published blue supergiant abundance studies in the Local Group and the Sculptor Group, a galaxy mass-metallicity relationship based solely on stellar spectroscopic studies is presented and compared with recent studies of Sloan Digital Sky Survey star-forming galaxies.
Abstract Copyright:
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Journal keyword(s):
galaxies: distances and redshifts - galaxies: individual: M81 - stars: abundances - stars: early-type
Nomenclature:
Tables 1-2: [KUG2012] ZNN, [KUG2012] CNN N=27.
Simbad objects:
47
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