J/ApJ/655/851 Wolf-Rayet galaxies in the SDSS (Zhang+, 2007)
Wolf-Rayet galaxies in the Sloan Digital Sky Survey:
the metallicity dependence of the initial mass function.
Zhang W., Kong X., Li C., Zhou H.-Y., Cheng F.-Z.
<Astrophys. J., 655, 851-862 (2007)>
=2007ApJ...655..851Z 2007ApJ...655..851Z
ADC_Keywords: Galaxies, spectra
Keywords: galaxies: abundances - galaxies: starburst - stars: Wolf-Rayet
Abstract:
We use a large sample of 174 Wolf-Rayet (W-R) galaxies drawn from the
Sloan Digital Sky Survey to study whether and how the slope of the
stellar initial mass function depends on metallicity. We calculate for
each object its oxygen abundance, according to which we divide our
sample into four metallicity subsamples. For each subsample, we then
measure three quantities: the equivalent width of the Hβ emission
line, the equivalent width of the W-R bump around 4650Å, and the W-R
bump-to-Hbeta intensity ratio, and compare to the predictions of the
same quantities by evolutionary synthesis models of Schaerer & Vacca
(1998ApJ...497..618S 1998ApJ...497..618S).
Description:
The data analyzed in this study are drawn from the SDSS.
Imaging is obtained in the u, g, r, i, and z bands with a special
purpose drift scan camera mounted on the SDSS 2.5m telescope at Apache
Point Observatory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 135 174 Parameters of the WR sample
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See also:
J/A+A/485/657 : Physical parameters of Wolf-Rayet galaxies (Brinchmann+, 2008)
J/A+AS/136/35 : WR galaxies and HII regions catalog (Schaerer+ 1999)
http://sdss.org : SDSS Home Page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- SDSS-ID The SDSS spectroscopic identification (1)
16- 20 F5.1 --- OII3727 ? The [OII] (3727Å) intensity (2)
22- 24 F3.1 --- H10 ? The H10 (3798Å) intensity (2)
26- 29 F4.1 --- H9 ? The H9 (3836Å) intensity (2)
31- 35 F5.1 --- H8 The H8 (3890Å) intensity (2)
37- 40 F4.1 --- H7 The H7 (3970Å) intensity (2)
42- 45 F4.1 --- Hd The Hδ (4100Å) intensity (2)
47- 50 F4.1 --- Hg The Hγ (4340Å) intensity (2)
52- 55 F4.1 --- OIII4363 ? The [OIII] (4363Å) intensity (2)
57- 61 F5.1 --- OIII4959 ? The [OIII] (4959Å) intensity (2)
63- 67 F5.1 --- OIII5007 ? The [OIII] (5007Å) intensity (2)
69- 73 F5.1 --- Ha ? The Hα (6563Å) intensity (2)
75- 78 F4.1 --- SII6717 The [SII] (6717Å) intensity (2)
80- 83 F4.1 --- SII6731 The [SII] (6731Å) intensity (2)
85- 88 F4.1 --- NII6548 The [NII] (6548Å) intensity (2)
90- 94 F5.1 --- NII6583 The [NII] (6583Å) intensity (2)
96- 99 F4.1 --- OII7320 ? The [OII] (7320Å) intensity (2)
101-103 F3.1 --- OII7330 ? The [OII] (7330Å) intensity (2)
105-111 F7.1 10-20W/m2 Hb Observed Hβ (4861Å) intensity (3)
113-117 F5.1 0.1nm EWHb The Hβ equivalent width
119-122 F4.1 --- W-R W-R bump (4650Å) intensity ratio (2)
124-127 F4.1 0.1nm EW4650 The blue W-R bump equivalent width
129-132 F4.2 [-] O/H The 12+log(O/H) abundance
134-135 A2 --- n_O/H Method used to estimate O/H (4)
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Note (1): In the MJD-Plate-Fiber format, from SDSS DR3.
Note (2): Relative to Hβ emission line, with I(Hβ)=100. Before
these quantities being measured, the observed spectra have been
corrected for the Galactic reddening, the internal reddening and the
stellar absorption. See the text for details. Blanks denote cases
in which Hα or [O III] (4959,5007) are clipped, or the
corresponding lines are not detected.
Note (3): Corrected for the Galactic reddening, but not for the internal
reddening.
Note (4): Method used as follows:
Te = Te method: from a determination of electron temperature and density
N2 = computation as O/H = 1.02log[I(NII)/I(Hα)] + 9.36
(van Zee et al., 1998AJ....116.2805V 1998AJ....116.2805V)
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History:
From electronic version of the journal
Positions have been retrieved with MJD-Plate-Fiber name at
http://skyserver.sdss.org/dr3/en/tools/crossid/speclist.asp
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 10-Dec-2008