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Query : 2002ApJS..142...35K |
2002ApJS..142...35K - Astrophys. J., Suppl. Ser., 142, 35-52 (2002/September-0)
Using strong lines to estimate abundances in extragalactic H II regions and starburst galaxies.
KEWLEY L.J. and DOPITA M.A.
Abstract (from CDS):
As we had shown, the commonly used abundance diagnostic R23 depends strongly on the ionization parameter, while the commonly used ionization parameter diagnostic [O III]/[O II] depends strongly on abundance. The iterative method of solution presented here allows both of these parameters to be obtained without recourse to the use of temperature-sensitive line ratios involving faint emission lines.
We compare three commonly used abundance diagnostic techniques and show that individually, they contain systematic and random errors. This is a problem affecting many abundance diagnostics, and the errors generally have not been properly studied or understood due to the lack of a reliable comparison abundance, except for very low metallicities, where the [O III] λ4363 auroral line is used. Here we show that the average of these techniques provides a fairly reliable comparison abundance indicator against which to test new diagnostic methods.
The cause of the systematic effects are discussed, and we present a new ``optimal'' abundance diagnostic method based on the use of line ratios involving [N II], [O II], [O III], [S II], and the Balmer lines. This combined diagnostic appears to suffer no apparent systematic errors, can be used over the entire abundance range and significantly reduces the random error inherent in previous techniques.
Finally, we give a recommended procedure for the derivation of abundances in the case that only spectra of limited wavelength coverage are available so that the optimal method can no longer be used.
Abstract Copyright: ∼
Journal keyword(s): Galaxies: Abundances - Galaxies: Evolution - Galaxies: Starburst - ISM: Abundances
Simbad objects: 2
Number of rows : 2 |
N | Identifier | Otype |
ICRS (J2000) RA |
ICRS (J2000) DEC |
Mag U | Mag B | Mag V | Mag R | Mag I | Sp type |
#ref
1850 - 2024 |
#notes |
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | NAME Magellanic Clouds | GrG | 03 00 | -71.0 | ~ | 7067 | 0 | |||||
2 | M 101 | GiP | 14 03 12.583 | +54 20 55.50 | 8.46 | 7.86 | 7.76 | ~ | 2914 | 2 |
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