J/A+A/545/A43 HII regions in NGC 628 and NGC 6946 (Cedres+, 2012)
Two-dimensional metallicity distribution of the ionized gas in NGC 628 and
NGC 6946.
Cedres B., Cepa J., Bongiovanni A., Castaneda H., Sanchez-Portal M.,
Tomita A.
<Astron. Astrophys., 545, A43 (2012)>
=2012A&A...545A..43C 2012A&A...545A..43C
ADC_Keywords: Galaxies, nearby ; H II regions ; Abundances
Keywords: galaxies: spiral - HII regions - galaxies: abundances -
galaxies: individual: NGC 628 - galaxies: individual: NGC 6946
Abstract:
We present here two HII region catalogues with azimuthal resolution
for the two grand design galaxies NGC 628 and NGC 6946. With the help
of these catalogues, we study several properties of the star-forming
processes occurring in spiral galaxies.
We obtained direct imaging in the narrow-band filters centred at Hα,
Hβ, [OII]λ3727, and [OIII]λλ4959, 5007 and
their respective continua. After the calibration and correction of the
data, we obtained for each HII region the de-reddened fluxes in the
aforementioned lines, the size, the Hα equivalent width, and,
using two different empirical calibrations, the metallicity. Employing
a method based on the Delaunay triangulation, a two-dimensional (2D)
representation of the metallicity was obtained.
Description:
Data for 209 H II regions of NGC 628 and 226 H II regions of NGC 6946
were obtained in an observing run during the period 2005 September
24-26 (inclusive) at the 2.5m Nordic Optical Telescope (NOT),
located at Roque de los Muchachos Observatory. The radial behaviours
of the Hα equivalent width, the excitation, and the oxygen
abundance are derived. Two-dimensional representations of the
metallicity and the excitation are calculated for the galaxies in the
study. The two empirical calibrations of the metallicity are compared.
Objects:
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RA (2000) DE Designation(s)
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01 36 41.77 +15 47 00.5 NGC 628 = M 74
20 34 52.33 +60 09 13.2 NGC 6946 = UGC 11597
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 52 209 Positions and main properties of the HII regions
of NGC 628
table5.dat 52 226 Positions and main properties of the HII regions
of NGC 6946
table6.dat 46 209 Equivalent width, Hβ flux and oxygen flux
ratios, both extinction corrected,
for all the HII regions of NGC 628
table7.dat 46 226 Equivalent width, Hβ flux and oxygen flux
ratios, both extinction corrected,
for all the HII regions of NGC 6946
table8.dat 24 209 *Values for the parameters P and R23, and the
metallicity derived through PT05 method for
all the HII regions of NGC 628
table9.dat 24 226 *Values for the parameters P and R23, and the
metallicity derived through PT05 method for
all the HII regions of NGC 6946
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Note on table8.dat and table9.dat: PT05: Pilyugin & Thuan, 2005ApJ...631..231P 2005ApJ...631..231P.
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See also:
J/A+AS/119/499 : NGC 628 and companions photometric distances (Sharina+ 1996)
J/AJ/120/1306 : NGC 628 HII regions (Lelievre+, 2000)
J/A+A/466/905 : HII regions in NGC 628 (Fathi+, 2007)
J/ApJ/669/525 : VRI photometric standards for NGC 6946 (Welch+, 2007)
Byte-by-byte Description of file: table4.dat table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number, within the galaxy
5- 11 F7.2 arcsec Xoff Offset along X
13- 19 F7.2 arcsec Yoff Offset along Y
21- 24 F4.2 arcmin R Deprojected radius
26- 31 F6.2 10-17W/m2 FHa Hα flux, extinction corrected
(in 10-14erg/cm2/s)
33- 36 F4.2 10-17W/m2 e_FHa rms uncertainty on FHa
38- 41 F4.2 mag AV Absorption in V band
43- 46 F4.2 mag e_AV rms uncertainty on AV
48- 52 F5.1 arcsec+2 Area Area
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Byte-by-byte Description of file: table6.dat table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number, within the galaxy
5- 8 F4.2 [0.1nm] [EWHa] Hα equivalent width (log scale)
10- 13 F4.2 [0.1nm] e_[EWHa] rms uncertainty on [EWHa]
15- 19 F5.2 10-17W/m2 FHb Hβ flux in (in 10-14erg/cm2/s)
21- 24 F4.2 10-17W/m2 e_FHb rms uncertainty on FHb
26- 30 F5.2 [-] [OII/Hb] ?=- Abundance ratio log([OII]/Hβ),
extinction corrected
32- 35 F4.2 [-] e_[OII/Hb] ? rms uncertainty on [OII]/Hb)
37- 41 F5.2 [-] [OIII/Hb] ?=- Abundance ratio log([OIII]/Hβ),
extinction corrected
43- 46 F4.2 [-] e_[OIII/Hb] ? rms uncertainty on [OIII/Hb]
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Byte-by-byte Description of file: table8.dat table9.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number, within the galaxy
5- 8 F4.2 -- P ?=- Excitation P parameter (1)
10- 14 F5.2 [-] logR23 ?=- R23 parameter (2)
16- 19 F4.2 [-] eps(O/H) ?=- Metallicity, 12+log(O/H)
21- 24 F4.2 [-] e_eps(O/H) ? rms uncertainty on 12+log(O/H)
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Note (1): Excitation P, defined as
P=[OIII]4959,5007/([OII]3727,3729+[OIII]4959,5007)
Note (2): R23 parameter, defined as
R23=([OII]3727,3729+[OIII]4959,5007)/Hβ
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Nov-2012