J/A+A/567/A88 Abundances in HII regions of M81 (Stanghellini+, 2014)
The radial metallicity gradient and the history of elemental enrichment
in M81 through emission-line probes.
Stanghellini L., Magrini L., Casasola V., Villaver E.
<Astron. Astrophys. 567, A88 (2014)>
=2014A&A...567A..88S 2014A&A...567A..88S
ADC_Keywords: Galaxies, nearby ; H II regions ; Abundances
Keywords: Galaxy: abundances - galaxies: evolution -
galaxies: individual: M81 - HII regions
Abstract:
We present a new set of weak-line abundances of HII regions in M81,
based on Gemini Multi-Object Spectrograph (GMOS) observations. The aim
is to derive plasma and abundance analysis for a sizable set of
emission-line targets to study the galactic chemical contents in the
framework of galactic metallicity gradients.
We used the weak-line abundance approach by deriving electron density
and temperatures for several HII regions in M81. Gradient analysis is
based on oxygen abundances.
Together with a set of HII region abundances determined similarly by
us with Multi-Mirror Telescope (MMT) spectra, the new data yield to a
radial oxygen gradient of -0.088±0.013dex/kpc, which is steeper than
the metallicity gradient obtained for planetary nebulae
(-0.044±0.007dex/kpc). This result could be interpreted as gradient
evolution with time: Models of galactic evolution with inside-out disk
formation associated to pre-enriched gas infall would produce such
difference of gradients, although stellar migration effects would also
induce a difference in the metallicity gradients between the old and
young populations.
Description:
The MOS spectroscopy of both M81 fields were acquired classically on
January 24, 2012, with GMOS-N at Mauna Kea. We employed both the R400
and B600 gratings in order to obtain the full spectral domain between
3200 and 9000Å needed for the science goals, and used 1" slitlets
with 2x2 binning.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 57 56 Regions with spectroscopy
table3.dat 40 1862 Observed fluxes and line intensities
table4.dat 30 600 Plasma analysis and abundances
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See also:
J/A+A/379/90 : Candidate Planetary Nebulae in M81 (Magrini+, 2001)
J/AJ/126/1286 : Hα+[NII] observations of M81 HII regions (Lin+, 2003)
J/A+A/521/A3 : Abundances in HII regions and PNe of M81 (Stanghellini+, 2010)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Region Region name (field 1: 1-27F1; field 2: 1-29F2)
5 A1 --- n_Region [b-g] Note (1)
7- 17 F11.7 deg RAdeg Right ascension (J2000)
18- 27 F10.7 deg DEdeg Declination (J2000)
28- 39 A12 --- Alias Possible earlier identification (2)
41 A1 --- Sp [Y/N] spectrum used (3)
43 A1 --- wl [YUN] Flag on weak-line abundances (4)
46- 50 F5.3 --- cbeta [0/2.5]?=- Hβ logarithmic extinction
53- 57 F5.3 --- e_cbeta ?=- rms uncertainty on cbeta
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Note (1): Notes as follows:
b = Hα emission is saturated
c = Considerable difference between B600 and R400 fluxes (∼50%)
d = Reddening correction not available
e = Hβ or Hα a non-Gaussian shape
f = Emission line diagnostics indicate that it might be a PN
g = This target shows a WR-type spectrum with stellar emission lines at
λ5812, and CIV features
Note (2): Names from:
[MPC2001] = Magrini et al (2001, Cat. J/A+A/379/90)
[IW2001] = Immler & Wang (2001, Cat. J/ApJ/554/202)
PSK = Petit et al. (1988A&AS...74..475P 1988A&AS...74..475P)
[PR95] = Perelmuter & Racine (1995, Cat. J/AJ/109/1055)
Note (3): Flag on spectrum as follows:
N = spectrum is not well characterized, thus we do not publish its line
fluxes in the tables (either the S/N was below 3 for the whole
spectrum, or a notable mismatch between the red and blue spectra was
noted)
Y = spectrum used
Note (4): Flag on weak-line abundances as follows:
N = weak-line abundances are not available
U = abundances have been calculated in conditions of very low S/N plasma
diagnostic lines for the temperatures, or if some of the major ionic
lines were missing, thus the derived total abundances were unreliable
(we still give the plasma diagnostic and ionic abundances in the
tables, but do not use them for gradients or average abundances)
Y = weak-line abundances calculated
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Region Region
6- 16 A11 --- Ion Ion
18- 21 I4 0.1nm lambda Wavelength λ
23- 28 F6.1 mW/m2 Flux ? Flux (erg/cm2/s)
30- 34 F5.1 mW/m2 e_Flux ? rms uncertainty in Flux
36- 40 F5.1 mW/m2 Int ? Intensity (erg/cm2/s)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Region Region name
6- 17 A12 --- Param Parameter name (1)
20- 28 E9.5 --- Value ? Parameter value
29- 30 A2 --- n_Value [NA] NA for not analysed
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Note (1): the parameters are, if "X" represents an element:
* abundances: 12+log(X/H), X/H
* ICF(X): Ionization Correction Factor
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Acknowledgements:
Letizia Stanghellini, lstanghellini(at)gmail.com
(End) Patricia Vannier [CDS] 24-Apr-2014