2012A&A...546A.122I

Query : 2012A&A...546A.122I

2012A&A...546A.122I - Astronomy and Astrophysics, volume 546A122-122 (2012/10-1)

Hunting for extremely metal-poor emission-line galaxies in the Sloan Digital Sky Survey: MMT and 3.5 M. APO observations.

IZOTOV Y.I., THUAN T.X. and GUSEVA N.G.

Abstract (from CDS):

We present 6.5-m MMT and 3.5m APO spectrophotometry of 69 HII regions in 42 low-metallicity emission-line galaxies, selected from the data release 7 of the Sloan Digital Sky Survey to have mostly [OIII]λ4959/Hβ≲ 1 and [NII]λ6583/Hβ≲0.1. The electron temperature-sensitive emission line [OIII]λ4363 is detected in 53 HII regions allowing a direct abundance determination. The oxygen abundance in the remaining 16 HII regions is derived using a semi-empirical method. The oxygen abundance of the galaxies in our sample ranges from 12+logO/H∼7.1 to ∼7.9, with 14 HII regions in 7 galaxies with 12+logO/H≤7.35. In 5 of the latter galaxies, the oxygen abundance is derived here for the first time. Including other known extremely metal-deficient emission-line galaxies from the literature, e.g. SBS 0335-052W, SBS 0335-052E and IZw18, we have compiled a sample of the 17 most metal-deficient (with 12+logO/H≤7.35) emission-line galaxies known in the local universe. There appears to be a metallicity floor at 12+logO/H∼6.9, suggesting that the matter from which dwarf emission-line galaxies formed was pre-enriched to that level by e.g. Population III stars.

Abstract Copyright: ∼

Journal keyword(s): galaxies: abundances - galaxies: irregular - galaxies: evolution - galaxies: ISM - HII regions - ISM: abundances

VizieR on-line data: <Available at CDS (J/A+A/546/A122): table1.dat table3a.dat table3b.dat table4a.dat table4b.dat table5a.dat table5b.dat table6.dat table7.dat table8.dat>

Simbad objects: 56

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Number of rows : 56
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 MCG+00-04-043 LSB 01 13 40.450 +00 52 39.16   17       ~ 65 0
2 SDSS J013835.01+002005.1 G 01 38 35.003 +00 20 05.19           ~ 4 0
3 SDSS J025428.94+003550.4 G 02 54 28.94 +00 35 50.4           ~ 5 0
4 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
5 [PBT2001] SBSG 0335-052 W G 03 37 38.40 -05 02 37.5   19.14     18.85 ~ 110 1
6 SBSG 0335-052B G 03 37 44.04 -05 02 40.2   16.77 16.65   16.79 ~ 220 1
7 SBSG 0335-052 AGN 03 37 44.06 -05 02 40.2     16.65     ~ 500 1
8 SDSS J081030.65+183704.2 AG? 08 10 30.654 +18 37 04.20           ~ 12 0
9 SDSS J081239.52+483645.3 bCG 08 12 39.532 +48 36 45.27           ~ 25 0
10 LEDA 4085865 AG? 08 33 35.647 +25 08 47.14           ~ 13 0
11 SDSS J083437.18+590536.0 bCG 08 34 37.218 +59 05 36.44           ~ 7 0
12 LEDA 3996864 AG? 08 43 37.973 +40 25 47.19           ~ 15 0
13 UGC 4557 AG? 08 51 03.591 +84 16 13.65   16.5       ~ 8 0
14 LEDA 1737674 AG? 09 06 00.918 +25 28 11.25           ~ 14 0
15 LEDA 2807128 LSB 09 08 36.54637 +05 17 26.9591   17.0       ~ 43 0
16 LEDA 4015419 LSB 09 26 10.3 +33 43 15           ~ 34 0
17 SDSS J093136.15+271746.6 AG? 09 31 36.153 +27 17 46.62           ~ 13 0
18 Mrk 116 AGN 09 34 02.1 +55 14 25           ~ 1179 1
19 UGC 5272 B AG? 09 50 19.484 +31 27 22.22   17.53       ~ 37 0
20 Z 153-5 AG? 09 56 46.047 +28 49 43.77 14.82 14.74 14.59 14.55 26.509 ~ 252 1
21 SDSS J095905.73+462650.5 G 09 59 05.738 +46 26 50.52           ~ 7 0
22 Z 153-10 G 09 59 26.46 +30 44 47.0 14.08 13.54 13.26 13.33   ~ 652 0
23 LEDA 29998 AGN 10 16 24.516 +37 54 45.96   16.5       ~ 62 0
24 Z 290-24 LSB 10 16 55.41082 +58 23 41.0699   15.6       ~ 16 0
25 Feige 34 HS* 10 39 36.7358839104 +43 06 09.212615280 9.613 10.91 11.14 11.319 11.464 sdOp 731 0
26 [ITS2007] 52339-578-60 EmG 10 44 57.79689 +03 53 13.1469           ~ 65 0
27 LEDA 4095638 AG? 10 56 40.349 +36 08 27.95   17.90       ~ 22 0
28 SDSS J105738.14+135844.5 G 10 57 38.146 +13 58 44.47           ~ 9 0
29 LEDA 5064998 AG? 11 09 09.523 +20 07 29.68           ~ 9 0
30 LEDA 1367320 EmG 11 19 28.100 +09 35 44.29           ~ 26 0
31 NAME Arp's Galaxy AG? 11 19 34.344 +51 30 12.17   17.3       ~ 78 0
32 SDSS J112146.67+374421.1 AG? 11 21 46.675 +37 44 21.16           ~ 7 0
33 MCG+10-17-011 AG? 11 32 02.6164558680 +57 22 36.292387908   17       ~ 64 1
34 LEDA 2171777 AG? 11 46 37.596 +40 50 36.65           ~ 9 0
35 LEDA 2284119 H2G 11 54 41.1914547048 +46 36 36.158901876           ~ 15 0
36 Z 269-49 AG? 12 15 46.626 +52 23 13.91   15.3       ~ 75 0
37 LEDA 101471 EmG 12 24 36.7369432538 +37 24 35.833921444           ~ 38 0
38 LEDA 40683 LSB 12 26 22.7 -01 15 13   16.3   16.0 15.9 ~ 32 0
39 LEDA 4015941 G 12 31 09.094 +42 05 33.91           ~ 16 0
40 SDSS J123552.35+275554.1 G 12 35 52.353 +27 55 54.18           ~ 3 0
41 NAME CVn I dwA GiC 12 38 40.06 +32 46 00.5 16.91 16.66 16.73 16.62   ~ 242 0
42 2dFGRS TGN127Z083 EmG 12 41 59.3495588664 -03 40 02.598496572   18.722   18.044   ~ 13 0
43 NGC 4656 GiP 12 43 57.6889089768 +32 10 13.345914504   10.96 10.52     ~ 385 3
44 LEDA 2790845 bCG 12 48 27.8 +48 23 01           ~ 10 0
45 SDSS J125740.55+334139.2 AG? 12 57 40.549 +33 41 39.22           ~ 10 0
46 HZ 44 HS* 13 23 35.2629445608 +36 07 59.544140304 10.186 11.42 11.65 12.00 11.995 sdBN0VIIHe28 439 0
47 SDSS J132723.28+402204.1 EmG 13 27 23.28574 +40 22 04.1469           ~ 7 0
48 [ITS2007] 53091-1464-370 EmG 13 31 26.9314785720 +41 51 48.242294892           ~ 11 0
49 HS 1353+4706 * 13 55 25.6 +46 51 51           M 3 0
50 LEDA 4004223 G 14 03 21.460 +58 04 03.42           ~ 5 0
51 2dFGRS TGN206Z232 bCG 14 14 54.149 -02 08 22.92   18.065   17.598   ~ 25 0
52 LEDA 2816094 AG? 14 22 38.8346401032 +54 14 09.220979148   18.5       ~ 35 0
53 SDSS J160810.36+352809.3 EmG 16 08 10.3514480208 +35 28 09.370755984           ~ 19 0
54 LEDA 1139658 G 21 04 55.310 -00 35 22.38           ~ 33 0
55 NAME Kinman Dwarf bCG 22 30 36.7959714600 -00 06 36.924915456 16.85 17.35 16.87   16.65 ~ 67 2
56 NAME Local Group GrG ~ ~           ~ 9325 0

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