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J/A+A/459/85   O/H and gas densities in star-forming galaxies (Nagao+, 2006)

Gas metallicity diagnostics in star-forming galaxies. Nagao T., Maiolino R., Marconi A. <Astron. Astrophys., 459, 85-101 (2006)> =2006A&A...459...85N
ADC_Keywords: Interstellar medium ; Abundances Keywords: galaxies: abundances - galaxies: evolution - galaxies: general - galaxies: ISM - H II regions Abstract: Generally the gas metallicity in distant galaxies can only be inferred by using a few prominent emission lines. Various theoretical models have been used to predict the relationship between emission line fluxes and metallicity, suggesting that some line ratios can be used as diagnostics of the gas metallicity in galaxies. However, accurate empirical calibrations of these emission line flux ratios from real galaxy spectra spanning a wide metallicity range are still lacking. In this paper we provide such empirical calibrations by using the combination of two sets of spectroscopic data: one consisting of low-metallicity galaxies with a measurement of [O III]λ4363 taken from the literature, including spectra from the Sloan Digital Sky Survey (SDSS), and the other one consisting of galaxies in the SDSS database whose gas metallicity has been determined from various strong emission lines in their spectra. This combined data set constitutes the largest sample of galaxies with information on the gas metallicity available so far and spanning the widest metallicity range. By using these data we obtain accurate empirical relations between gas metallicity and several emission line diagnostics, including the R23 parameter, the [NII]λ6584/Hα and [O III]λ5007/[NII]λ6584 ratios. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 82 157 Re-calculated properties of the compiled low-metallicity galaxies refs.dat 132 20 References
See also: : SDSS Home Page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 18 A18 --- Name Object name 20- 25 F6.3 --- R23 R23 parameter (1) 27- 31 F5.3 --- e_R23 rms uncertainty on R23 33 A1 --- l_nH(s+) Limit flag on nH(s+) 34- 37 I4 cm-3 nH(s+) Gas density of the S+ regions 39- 42 I4 cm-3 E_nH(s+) ? Error on nH(s+) (upper limit) 44- 46 I3 cm-3 e_nH(s+) ? Error on nH(s+) (lower limit) 47 A1 --- n_nH(s+) [d] d: Adopted flux (2) 49- 53 F5.3 10+4K t(O2+) Gas temperature of the O2+ regions 55- 59 F5.3 10+4K E_t(O2+) Error on t(O2+) (upper limit) 61- 65 F5.3 10+4K e_t(O2+) Error on t(O2+) (lower limit) 67- 71 F5.3 --- 12+log(O/H) (O/H) abundance 73- 77 F5.3 --- e_12+log(O/H) rms uncertainty on 12+log(O/H) 79- 82 A4 --- Ref Reference, in refs.dat file
Note (1): R23 = {F([OII]3727)+F[OIII]4959)+F[OIII]5007)}/F(Hbeta4861), where F denotes the emission-line flux. Note (2): Flux ratio of [S II] is not given in literature. We adopt nH(S+)=10cm-3 to calculate the oxygen abundance for these objects.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Ref Reference code 6- 24 A19 --- BibCode BibCode 26- 50 A25 --- Aut Author's name 54-132 A79 --- Com Comments
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 11-May-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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