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 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:
http://www.sdss.org : 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