J/ApJ/675/1213 Abundances in M33 HII regions (Rosolowsky+, 2008)
The M33 metallicity project: resolving the abundance gradient discrepancies in
M33.
Rosolowsky E., Simon J.D.
<Astrophys. J., 675, 1213-1222 (2008)>
=2008ApJ...675.1213R 2008ApJ...675.1213R
ADC_Keywords: Galaxies, nearby ; H II regions ; Abundances
Keywords: galaxies: abundances - galaxies: individual (M33) - galaxies: spiral -
H II regions - ISM: abundances - ISM: evolution
Abstract:
We present a new determination of the metallicity gradient in M33,
based on Keck LRIS measurements of oxygen abundances using the
temperature-sensitive emission line [OIII] λ4363 in 61 HII
regions. These data approximately triple the sample of direct oxygen
abundances in M33. We find a central abundance of
12+log(O/H)=8.36±0.04 and a slope of -0.027±0.012dex/kpc, in
agreement with infrared measurements of the neon abundance gradient
but much shallower than most previous oxygen gradient measurements.
There is substantial intrinsic scatter of 0.11dex in the metallicity
at any given radius in M33, which imposes a fundamental limit on the
accuracy of gradient measurements that rely on small samples of
objects. We also show that the ionization state of neon does not
follow the ionization state of oxygen as is commonly assumed,
suggesting that neon abundance measurements from optical emission
lines require careful treatment of the ionization corrections.
Description:
The M33 Metallicity Project is a long-term program in which we plan to
obtain deep spectroscopy of ∼1000 HII regions in M33 drawn from the
unified catalog of Hodge et al. (2002, An Atlas of Local Group
Galaxies (Dordrecht: Kluwer)).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 126 63 HII region line fluxes
table2.dat 99 63 Balmer series line ratios and derived properties
--------------------------------------------------------------------------------
See also:
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/PASP/111/685 : HII regions of M33. II. (Hodge+, 1999)
J/A+A/512/A63 : Abundances of M33 HII regions (Magrini+, 2010)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/61] Sequential number
3 A1 --- n_Seq [d] Same object observed on multiple
slit masks
5- 6 I2 h RAh Right ascension (J2000.0) (1)
8- 9 I2 min RAm Right ascension (J2000.0) (1)
11- 14 F4.1 s RAs Right ascension (J2000.0) (1)
16 A1 --- DE- Declination sign (J2000.0) (1)
17- 18 I2 deg DEd Declination (J2000.0) (1)
20- 21 I2 arcmin DEm Declination (J2000.0) (1)
23- 24 I2 arcsec DEs Declination (J2000.0) (1)
26- 31 A6 --- Name Cross-identifications (2)
33- 36 F4.2 kpc Rgal Galactocentric distance
38- 42 F5.3 --- F[OII] Flux of [OII]λ3727 line (3)
44- 48 F5.3 --- e_F[OII] rms uncertainty on F[OII]
50- 55 F6.4 --- F[NeIII] Flux of [NeIII]λ3869 line (3)
57- 62 F6.4 --- e_F[NeIII] rms uncertainty on F[NeIII]
64- 70 F7.5 --- F[OIII]1 Flux of [OIII]λ 4363 (3)
72- 77 F6.4 --- e_F[OIII]1 rms uncertainty on F[OIII]
79- 84 F6.4 --- F[OIII]2 Flux of [OIII]λ 4959 (3)
86- 91 F6.4 --- e_F[OIII]2 rms uncertainty on F[OIII]
93- 98 F6.4 --- F[OIII]3 Flux of [OIII]λ 5007 (3)
99-104 F6.4 --- e_F[OIII]3 rms uncertainty on F[OIII]
105-109 I5 K Te([OIII]) Electron temperature, from [OIII] lines
111-114 I4 K e_Te([OIII]) rms uncertainty on Te([OIII])
116-120 F5.3 --- eps(O) Oxygen abundance{epsilson}(O)=12+log(O/H)
122-126 F5.3 --- e_eps(O) rms uncertainty on oxygen abundance
--------------------------------------------------------------------------------
Note (1): Actual position observed based on targets identified in the Local
Group Survey images of Massey et al. (2006, Cat. J/AJ/131/2478).
Note (2): Closest matching cataloged HII region for observed coordinates.
Catalog abbreviations are:
MA = Mayall & Aller (1942ApJ....95....5M 1942ApJ....95....5M), [MA42] NNa in Simbad
S = Searle (1971ApJ...168..327S 1971ApJ...168..327S), [S71] M 33 NN in Simbad
B = Boulesteix et al. (1974A&A....37...33B 1974A&A....37...33B), BCLMP NNNNA in Simbad
C = Courtes et al. (1987A&A...174...28C 1987A&A...174...28C), CPSDP NNNA in Simbad
Full designations of substructure within individual HII regions
(indicated by the letters at the end of the catalog names) are taken
from Hodge et al. (2002, An Atlas of Local Group Galaxies (Dordrecht:
Kluwer)).
Note (3): Extinction-corrected line fluxes relative to Hβ=1.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/61] Running identification number
4 A1 --- f_EWHb [b] b when equivalent width was poorly defined
6- 12 F7.2 0.1nm EWHb ? Hβ emission line equivalent width
14- 19 F6.2 0.1nm e_EWHb ? Uncertainty in EWHb
21- 25 F5.3 --- cHb Hβ reddening correction
27- 31 F5.3 --- e_cHb Uncertainty in cHb
33- 37 F5.2 0.1nm EW* Stellar absorption equivalent width
39- 43 F5.2 0.1nm e_EW* Uncertainty in EW*
45- 50 F6.4 --- OHg Observed Hγ relative to Hβ
52- 57 F6.4 --- OHd Observed Hδ relative to Hβ
59- 65 F7.4 --- OH7 Observed H7 relative to Hβ
67- 74 F8.5 --- OH9 Observed H9 relative to Hβ
76- 80 F5.3 --- Hgc Extinction/Absorption corrected Hγ
82- 86 F5.3 --- Hdc Extinction/Absorption corrected Hδ
88- 92 F5.3 --- H7c Extinction/Absorption corrected H7
94- 99 F6.4 --- H9c Extinction/Absorption corrected H9
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 10-Jul-2010