J/ApJ/758/133 Metallicity profile of M31 HII regions and PNe (Sanders+, 2012)
The metallicity profile of M31 from spectroscopy of hundreds of HII regions
and PNe.
Sanders N.E., Caldwell N., McDowell J., Harding P.
<Astrophys. J., 758, 133 (2012)>
=2012ApJ...758..133S 2012ApJ...758..133S
ADC_Keywords: Abundances ; H II regions ; Planetary nebulae ; Spectroscopy ;
Galaxies, nearby ; Cross identifications
Keywords: galaxies: abundances; galaxies: evolution; galaxies: individual: M 31;
H II regions; planetary nebulae: general
Abstract:
The oxygen abundance gradients among nebular emission line regions in
spiral galaxies have been used as important constraints for models of
chemical evolution. We present the largest-ever full-wavelength
optical spectroscopic sample of emission line nebulae in a spiral
galaxy (M31). We have collected spectra of 253 HII regions and 407
planetary nebulae (PNe) with the Hectospec multi-fiber spectrograph of
the MMT. We measure the line-of-sight extinction for 199 HII regions
and 333 PNe; we derive oxygen abundance directly, based on the
electron temperature, for 51 PNe; and we use strong-line methods to
estimate oxygen abundance for 192 HII regions and nitrogen abundance
for 52 HII regions. The relatively shallow oxygen abundance gradient
of the more extended HII regions in our sample is generally in
agreement with the result of Zaritsky et al. (1994ApJ...420...87Z 1994ApJ...420...87Z),
based on only 19 M31 HII regions, but varies with the strong-line
diagnostic employed. Our large sample size demonstrates that there is
significant intrinsic scatter around this abundance gradient, as much
as ∼3 times the systematic uncertainty in the strong-line diagnostics.
The intrinsic scatter is similar in the nitrogen abundances, although
the gradient is significantly steeper. On small scales (deprojected
distance <0.5kpc), HII regions exhibit local variations in oxygen
abundance that are larger than 0.3dex in 33% of neighboring pairs. We
do not identify a significant oxygen abundance gradient among PNe, but
we do find a significant gradient in the [NII] ratio that varies
systematically with surface brightness. Our results underscore the
complex and inhomogeneous nature of the interstellar medium of M31,
and our data set illustrates systematic effects relevant to future
studies of the metallicity gradients in nearby spiral galaxies.
Description:
Small, resolved objects and unresolved Hα features were selected
as HII region candidates by inspecting the images of the Local Group
Galaxies Survey (LGGS; Massey et al. 2007, Cat. J/AJ/134/2474).
Additionally, some objects observed as part of the M31 cluster survey
of Caldwell et al. (2009, Cat. J/AJ/137/94) had strong emission, and
are included in the present study. Some objects from the planetary
nebula (PN) catalog of Merrett et al. (2006, Cat. J/MNRAS/369/120) as
well as strong and unresolved [OIII] features from the LGGS images
were observed as PN candidates.
Optical spectra were obtained, from 2004 to 2011, with the Hectospec
multi-fiber positioner and spectrograph on the 6.5m MMT telescope. The
Hectospec 270gpm grating was used and provided spectral coverage from
3650 to 9200Å at a resolution of ∼5Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 110 738 Basic data for M31 HII regions and PNe
(corrected version; 16-Mar-2015)
table2.dat 146 738 Measured line fluxes for M31 HII regions and
PNe, relative to Hβ
table3.dat 86 253 Derived quantities for M31 HII regions
table4.dat 26 460 Derived quantities for M31 planetary nebulae
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See also:
J/AJ/142/139 : A new catalog of HII regions in M31 (Azimlu+, 2011)
J/ApJ/724/748 : Galactic anticenter PNe and oxygen abundance (Henry+, 2010)
J/AJ/137/94 : Star clusters in M31 (Caldwell+, 2009)
J/ApJ/689/194 : Distances of galactic planetary nebulae (Stanghellini+, 2008)
J/AJ/134/2474 : Hα emission-line stars in dwarf galaxies (Massey+, 2007)
J/A+A/471/127 : New globular clusters in M31 (Galleti+, 2007)
J/A+A/459/85 : O/H and gas densities in star-forming galaxies (Nagao+, 2006)
J/MNRAS/369/120 : Kinematic survey of PNe in M31 (Merrett+, 2006)
J/MNRAS/369/97 : M31 planetary nebulae velocities (Halliday+, 2006)
J/MNRAS/358/521 : Chemical evolution models for galaxies (Molla+, 2005)
J/ApJ/617/240 : Oxygen abundances in GOODS-North (Kobulnicky+, 2004)
J/ApJ/616/804 : Planetary Nebula Kinematics in M31 (Hurley-Keller+, 2004)
J/A+AS/102/251 : Objective-prism survey of M31 em. objects (Meyssonnier+ 1993)
J/A+AS/92/625 : Ionized nebulae in M31 (Walterbos+ 1992)
J/ApJS/38/351 : M31 planetary nebulae (Ford+, 1978)
J/A+AS/31/439 : A Survey of HII Regions in M31 (Pellet+ 1978)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 35 A35 --- Type source type ("HII regions", "Planetary nebulae",
"Planetary nebulae (halo population)", or
"Unclassified")
37- 42 A6 --- ID Source identifier (HIINNN, PNNNN, PNhNNN or
XNNN; <[SCM2012b] {ID}> in Simbad)
44 I1 h RAh Hour of Right Ascension (J2000)
46- 47 I2 min RAm Minute of Right Ascension (J2000)
49- 53 F5.2 s RAs Second of Right Ascension (J2000)
55 A1 --- DE- Sign of the Declination (J2000)
56- 57 I2 deg DEd Degree of Declination (J2000)
59- 60 I2 arcmin DEm Arcminute of Declination (J2000)
62- 65 F4.1 arcsec DEs Arcsecond of Declination (J2000)
67- 71 F5.1 kpc Grad Galactocentric radius; see Section 2.3
73 A1 --- M [ds] diffuse or stellar morphology (1)
75 I1 --- SB [1/3] Surface brightness class
(1="dim", 2="normal", 3="bright") (2)
77 A1 --- ADC [ny] Status of Atmospheric Dispersion
Compensator (y=ADC was functioning) (3)
79- 84 F6.1 km/s Vel [-640/232]? Velocity
86- 95 A10 --- M06 Merrett et al. 2006, Cat. J/MNRAS/369/120,
ID number (<[MMD2006] NNNN> in Simbad)
97-102 A6 --- RBC Galeti et al. 2007, Cat. J/A+A/471/127, Revised
Bologna Catalog name
104-110 A7 --- AMB Azimlu et al. 2011, Cat. J/AJ/142/139, ID number
(<[AMB2011] HII NNNN> or
<[AMB2011] NNN> in Simbad)
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Note (1): Based on LGGS Hα imaging, as described in Section 2.2.
Objects whose Hα emission appears unresolved at the resolution
of these images (∼1'') are classified as "stellar" and those that
appear extended and nebulous are classified as "diffuse."
Note (2): As defined in Section 2.4 based on the Hα flux.
Note (3): During the observation of the object.
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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- 35 A35 --- Type Source type (as in table 1)
37- 42 A6 --- ID Source identifier (as in table 1)
44- 49 F6.1 --- 3727 [15/1230]? The [OII]3727Å line ratio (4)
51- 54 F4.1 --- e_3727 [0.8/90]? Uncertainty in [OII]3727
56- 60 F5.1 --- 4363 [0.6/100]? The [OIII]4363Å line ratio (4)
62- 65 F4.1 --- e_4363 ? Uncertainty in [OIII]4363
67- 71 F5.1 --- 4959 [4/880]? The [OIII]4959Å line ratio (4)
73- 76 F4.1 --- e_4959 ? Uncertainty in [OIII]4959
78- 83 F6.1 --- 5007 [8/2640]? The [OIII]5007Å line ratio (4)
85- 88 F4.1 --- e_5007 ? Uncertainty in [OIII]5007
90- 94 F5.1 --- 6548 [5/450]? The [NII]6548Å line ratio (4)
96- 99 F4.1 --- e_6548 ? Uncertainty in [NII]6548
101-104 I4 --- Ha [100/1290]? The Hα line ratio (4)
106-108 I3 --- e_Ha ? Uncertainty in Ha
110-115 F6.1 --- 6584 [8/1420]? The [NII]6584Å line ratio (4)
117-120 F4.1 --- e_6584 ? Uncertainty in [NII]6584
122-127 F6.2 --- 6717 [3/230]? The [SII]6717Å line ratio (4)
129-133 F5.2 --- e_6717 ? Uncertainty in [SII]6717
135-140 F6.2 --- 6731 [2.9/160]? The [SII]6731Å line ratio (4)
142-146 F5.2 --- e_6731 ? Uncertainty in [SII]6731
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Note (4): Extinction correction has not been applied. Line fluxes are
reported relative to Hβ=100; however, line flux ratios for lines
with large wavelength separations are unreliable for spectra where the
ADC was not functioning (see Table 1). For objects where Hβ is
not detected, fluxes are instead normalized relative to another line
whose flux is given as 100.
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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- 6 A6 --- ID HII identifier (HIINNN)
8- 11 F4.2 mag AV [0/4.7]? The V band extinction
13- 16 F4.2 mag e_AV ? Uncertainty in AV
18- 21 F4.2 [-] eps(O) ? Direct ε(O)=log(O/H)+12
oxygen number abundance estimation (G1)
23- 26 F4.2 [-] e_eps(O) ? Uncertainty in eps(O) (G1)
28- 31 F4.2 [-] Z94 ? Zaritsky et al 1994ApJ...420...87Z 1994ApJ...420...87Z
oxygen abundance estimation (G1)
33- 36 F4.2 [-] e_Z94 ? Uncertainty in Z94 (G1)
38- 41 F4.2 [-] KD02 ? Kewley & Dopita 2002ApJS..142...35K 2002ApJS..142...35K
oxygen abundance estimation (G1)
43- 46 F4.2 [-] e_KD02 ? Uncertainty in KD02 (G1)
48- 51 F4.2 [-] N06-N2 ? Nagao et al. 2006, Cat. J/A+A/459/85, N2
oxygen abundance estimation (G1)
53- 56 F4.2 [-] e_N06-N2 ? Uncertainty in N06-N2 (G1)
58- 61 F4.2 [-] N06-O3N2 ? Nagao et al. 2006, Cat. J/A+A/459/85, O3N2
oxygen abundance estimation (G1)
63- 66 F4.2 [-] e_N06-O3N2 ? Uncertainty in N06-O3N2 (G1)
68- 71 F4.2 [-] PT05 ? Pilyugin & Thuan 2005ApJ...631..231P 2005ApJ...631..231P
oxygen abundance estimation (G1)
73- 76 F4.2 [-] e_PT05 ? Uncertainty in PT05 (G1)
78- 81 F4.2 [-] PVT-ONS ? Pilyugin et al. 2010ApJ...720.1738P 2010ApJ...720.1738P
Nitrogen abundance estimation (G1)
83- 86 F4.2 [-] e_PVT-ONS ? Uncertainty in PVT-ONS (G1)
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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- 6 A6 --- ID PN identifier (PNNNN or PNhNNN)
8- 11 F4.2 mag AV [0/4]? The V band extinction
13- 16 F4.2 mag e_AV ? Uncertainty in AV
18- 21 F4.2 [-] eps(O) ? Oxygen abundance log(O/H)+12 (G1)
23- 26 F4.2 [-] e_eps(O) ? Uncertainty in eps(O) (G1)
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Global note:
Note (G1): The abundance diagnostics applied in this table are described in
Section 2.7. The reported uncertainties are derived by propagation of
the line flux uncertainties, as described in Section 2.7 and does not
include other systematic effects. When this "statistical" uncertainty
is less than 0.01dex, we do not report it.
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History:
* 08-Jul-2014: From electronic version of the journal
* 27-Aug-2014: Insert into VizieR
* 08-Dec-2014: Table 1 corrected (col. AMB was truncated)
* 02-Feb-2015: Table 1 corrected (col. AMB was still truncated)
* 16-Mar-2015: Table 1 corrected (few AMB cross-identifications);
we acknowledge Nathan Sanders (CfA) for the corrected versions.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Jul-2014