J/A+A/448/955 Abundances of emission galaxies in SDSS-DR3 (Izotov+, 2006)
The chemical composition of metal-poor emission-line galaxies in the
Data Release 3 of the Sloan Digital Sky Survey.
Izotov Y.I., Stasinska G., Meynet G., Guseva N.G., Thuan T.X.
<Astron. Astrophys. 448, 955 (2006)>
=2006A&A...448..955I 2006A&A...448..955I
ADC_Keywords: Galaxies, spectra ; H II regions ; Abundances
Keywords: galaxies: ISM - galaxies: starburst - galaxies: abundances
Abstract:
We have re-evaluated empirical expressions for the abundance
determination of N, O, Ne, S, Cl, Ar and Fe taking into account
the latest atomic data and constructing an appropriate grid of
photoionization models with state-of-the art model atmospheres.
Using these expressions we have derived heavy element abundances in
the ∼310 emission-line galaxies from the Data Release 3 of the Sloan
Digital Sky Survey (SDSS, III/241) with an observed Hbeta flux
F(Hbeta)>10-14erg/s/cm2 and for which the [O III] 4363 emission
line was detected at least at a 2sigma level, allowing abundance
determination by direct methods. The oxygen abundance 12+logO/H of the
SDSS galaxies lies in the range from ∼7.1 (Z☉/30) to ∼8.5
(0.7Z☉). The SDSS sample is merged with a sample of 109 blue
compact dwarf (BCD) galaxies with high quality spectra, which contains
extremely low-metallicity objects. We use the merged sample to study
the abundance patterns of low-metallicity emission-line galaxies. We
find that extremely metal-poor galaxies (12+logO/H<7.6, i.e.
Z<Z☉/12) are rare in the SDSS sample. The alpha element to
oxygen abundance ratios do not show any significant trends with oxygen
abundance, in agreement with previous studies, except for a slight
increase of Ne/O with increasing metallicity, which we interpret as
due to a moderate depletion of O onto grains in the most metal-rich
galaxies. The Fe/O abundance ratio is smaller than the solar value, by
up to 1 dex at the high metallicity end. We also find that Fe/O
increases with decreasing Hbeta equivalent width EW(Hbeta). We
interpret this as a sign of strong depletion onto dust grains, and
gradual destruction of those grains on a time scale of a few Myr. All
the galaxies are found to have logN/O>-1.6, implying that they have a
different nature than the subsample of high-redshift damped Lyalpha
systems with log N/O of ~-2.3 and that their ages are larger than
100-300Myr. We confirm the apparent increase in N/O with decreasing
EW(Hbeta), already shown in previous studies, and explain it as the
signature of gradual nitrogen ejection by massive stars from the most
recent starburst.
Description:
Table 1 contains emission line fluxes, the equivalent width and the
observed flux of the Hbeta emission line and the extinction
coefficient obtained from the spectra of the SDSS galaxies.
Table 2 contains the electron temperature Te(O III), the oxygen
abundance 12+logO/H, and the logarithms of the N/O, Ne/O, S/O, Cl/O,
Ar/O, Fe/O abundance ratios in the SDSS galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sdss.dat 54 309 *SDSS-DR3 names and positions
table1.dat 332 309 Extinction-corrected fluxes of the emission
lines in the spectra of the SDSS galaxies
table2.dat 104 309 Element abundances in the SDSS galaxies
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Note on sdss.dat: table added at CDS
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See also:
II/259 : The SDSS Photometric Catalog, Release 3 (Abazajian+ 2005)
III/241 : Spectroscopy of SDSS Data Release 3 (SDSS-DR3) (ARC, 2005)
http://www.sdss.org/dr3/ : SDSS-R3 Home Page
Byte-by-byte Description of file: sdss.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name The spectrum number in the SDSS database
16- 24 F9.5 deg RAdeg ? Right Ascension (J2000) from SDSS-DR3 (1)
26- 34 F9.5 deg DEdeg ? Declination (J2000) from SDSS-DR3 (1)
36- 54 A19 --- SDSS SDSS name from SDSS-DR3 (1)
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Note (1): One spectrum number, 0412-51931-038, could not be located in any
of the releases DR2, DR3 and DR4, and had therefore no position.
The SDSS name, based on J2000 position, exists only for the objects
existing in the SDSS-DR3 (Cat. II/259)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name The spectrum number in the SDSS database
16- 20 F5.3 --- F3727 Extinction-corrected flux of the
[O II] 3727 line relative to Hbeta
22- 26 F5.3 --- e_F3727 rms uncertainty on [O II] 3727 flux
28- 32 F5.3 --- F3750 Extinction-corrected flux of the
H12 3750 line relative to Hbeta
34- 38 F5.3 --- e_F3750 rms uncertainty on H12 3750 flux
40- 44 F5.3 --- F3771 Extinction-corrected flux of the
H11 3771 line relative to Hbeta
46- 50 F5.3 --- e_F3771 rms uncertainty on H11 3771 flux
52- 56 F5.3 --- F3797 Extinction-corrected flux of the
H10 3797 line relative to Hbeta
58- 62 F5.3 --- e_F3797 rms uncertainty on H10 3797 flux
64- 68 F5.3 --- F3835 Extinction-corrected flux of the
H9 3835 line relative to H beta
70- 74 F5.3 --- e_F3835 rms uncertainty on H9 3835 flux
76- 80 F5.3 --- F3868 Extinction-corrected flux of the
[Ne III] 3868 line relative to Hbeta
82- 86 F5.3 --- e_F3868 rms uncertainty on [Ne III] 3868 flux
88- 92 F5.3 --- F4101 Extinction-corrected flux of the
Hdelta 4101 line relative to Hbeta
94- 98 F5.3 --- e_F4101 rms uncertainty on Hdelta 4101 flux
100-104 F5.3 --- F4340 Extinction-corrected flux of the
Hgamma 4340 line relative to Hbeta
106-110 F5.3 --- e_F4340 rms uncertainty on Hgamma 4340 flux
112-116 F5.3 --- F4363 Extinction-corrected flux of the
[O III] 4363 line relative to Hbeta
118-122 F5.3 --- e_F4363 rms uncertainty on [O III] 4363 flux
124-128 F5.3 --- F4658 Extinction-corrected flux of the
[Fe III] 4658 line relative to Hbeta
130-134 F5.3 --- e_F4658 rms uncertainty on [Fe III] 4658 flux
136-140 F5.3 --- F4686 Extinction-corrected flux of the
He II 4686 line relative to Hbeta
142-146 F5.3 --- e_F4686 rms uncertainty on He II 4686 flux
148-152 F5.3 --- F4740 Extinction-corrected flux of the
[Ar IV] 4740 line relative to Hbeta
154-158 F5.3 --- e_F4740 rms uncertainty on [Ar IV] 4740 flux
160-164 F5.3 --- F4861 [1.0] Extinction-corrected flux of the
Hbeta 4861 line relative to Hbeta
166-170 F5.3 --- e_F4861 rms uncertainty on Hbeta 4861 flux
172-176 F5.3 --- F4959 Extinction-corrected flux of the
[O III] 4959 line relative to Hbeta
178-182 F5.3 --- e_F4959 rms uncertainty on [O III] 4959 flux
184-188 F5.3 --- F4988 Extinction-corrected flux of the
[Fe III] 4988 line relative to Hbeta
190-194 F5.3 --- e_F4988 rms uncertainty on [Fe III] 4988 flux
196-200 F5.3 --- F5525 Extinction-corrected flux of the
[Cl III] 5517+5538 lines relative to Hbeta
202-206 F5.3 --- e_F5525 rms uncertainty on [Cl III] 5517+5538 flux
208-212 F5.3 --- F5876 Extinction-corrected flux of the
He I 5876 line relative to Hbeta
214-218 F5.3 --- e_F5876 rms uncertainty on He I 5876 flux
220-224 F5.3 --- F6300 Extinction-corrected flux of the
[O I] 6300 line relative to Hbeta
226-230 F5.3 --- e_F6300 rms uncertainty on [O I] 6300 flux
232-236 F5.3 --- F6312 Extinction-corrected flux of the
[S III] 6312 line relative to Hbeta
238-242 F5.3 --- e_F6312 rms uncertainty on [S III] 6312 flux
244-248 F5.3 --- F6563 Extinction-corrected flux of the
Halpha 6563 line relative to Hbeta
250-254 F5.3 --- e_F6563 rms uncertainty on Halpha 6563 flux
256-260 F5.3 --- F6584 Extinction-corrected flux of the
[N II] 6584 line relative to Hbeta
262-266 F5.3 --- e_F6584 rms uncertainty on [N II] 6584 flux
268-272 F5.3 --- F6725 Extinction-corrected flux of the
[S II] 6717+6731 lines relative to Hbeta
274-278 F5.3 --- e_F6725 rms uncertainty on [S II] 6717+6731 flux
280-284 F5.3 --- F7136 Extinction-corrected flux of the
[Ar III] 7136 line relative to Hbeta
286-290 F5.3 --- e_F7136 rms uncertainty on [Ar III] 7136 flux
292-296 F5.3 --- F7325 Extinction-corrected flux of the
[O II] 7320+7331 lines relative to Hbeta
298-302 F5.3 --- e_F7325 rms uncertainty on [O II] 7320+7331 flux
304-308 F5.3 --- F9069 Extinction-corrected flux of the
[S III] 9069 line relative to Hbeta
310-314 F5.3 --- e_F9069 rms uncertainty on [S III] 9069 flux
316-319 F4.0 0.1nm EWHb Equivalent width of the Hbeta emission line
321-325 F5.0 10-19W/s/m2 FHb Observed Hbeta flux
327-332 F6.3 --- cHb Extinction coefficient
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name The spectrum number in the SDSS database
16- 21 F6.4 10-4K Te Electron temperature Te(O III)
23- 28 F6.4 10-4K e_Te rms uncertainty on Te(O III)
30- 33 F4.2 --- 12+logO/H Oxygen abundance 12+logO/H
35- 38 F4.2 --- e_12+logO/H rms uncertainty on oxygen abundance 12+logO/H
40- 44 F5.2 --- logN/O Logarithm of the nitrogen-to-oxygen
abundance ratio logN/O
46- 49 F4.2 --- e_logN/O rms uncertainty on logN/O
51- 55 F5.2 --- logNe/O Logarithm of the neon-to-oxygen
abundance ratio logNe/O
57- 60 F4.2 --- e_logNe/O rms uncertainty on logNe/O
62- 66 F5.2 --- logS/O Logarithm of the sulfur-to-oxygen
abundance ratio logS/O
68- 71 F4.2 --- e_logS/O rms uncertainty on logS/O
73- 77 F5.2 --- logAr/O Logarithm of the argon-to-oxygen
abundance ratio logAr/O
79- 82 F4.2 --- e_logAr/O rms uncertainty on logAr/O
84- 88 F5.2 --- logCl/O Logarithm of the chlorine-to-oxygen
abundance ratio logCl/O
90- 93 F4.2 --- e_logCl/O rms uncertainty on logCl/O
95- 99 F5.2 --- logFe/O Logarithm of the iron-to-oxygen
abundance ratio logFe/O
101-104 F4.2 --- e_logFe/O rms uncertainty on logFe/O
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Acknowledgements: Yuri Izotov, izotov(at)astro.physik.uni-goettingen.de
(End) Yuri Izotov [MAO, Ukraine], Patricia Vannier [CDS] 22-Nov-2005