2007ApJ...665.1115I

Query : 2007ApJ...665.1115I

2007ApJ...665.1115I - Astrophys. J., 665, 1115-1128 (2007/August-3)

MMT observations of new extremely metal-poor emission-line galaxies in the Sloan Digital Sky Survey.

IZOTOV Y.I. and THUAN T.X.

Abstract (from CDS):

We present 6.5 m MMT spectrophotometry of 20 H II regions in 13 extremely metal-poor emission-line galaxies selected from Data Release 5 of the Sloan Digital Sky Survey to have [O III] λ4959/Hβ≲1 and [N II] λ6583/Hβ≲0.05. The electron-temperature-sensitive emission line [O III] λ4363 is detected in 13 H II regions, allowing a direct abundance determination. The oxygen abundance in the remaining H II regions is derived using a semiempirical method. The oxygen abundance of the galaxies in our sample ranges from 12+log(O/H)∼7.1 to ∼7.8, with 10 H II regions having an oxygen abundance lower than 7.5. The lowest oxygen abundances, 7.14±0.03 and 7.13±0.07, are found in two H II regions of the blue compact dwarf galaxy SDSS J0956+2849 (≡DDO 68), making it the second most metal-deficient emission-line galaxy known, after SBS 0335-052W.

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Journal keyword(s): Galaxies: Abundances - Galaxies: Evolution - Galaxies: Formation - Galaxies: Irregular - Galaxies: ISM - ISM: H II Regions - ISM: Abundances

Simbad objects: 21

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Number of rows : 21
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 Mrk 996 Sy1 01 27 35.5248944352 -06 19 35.432857848 14.75 15.05 14.48 14.06 13.70 ~ 136 0
3 LEDA 7896 AG? 02 04 25.598 -10 09 35.01   17       ~ 21 0
4 SDSS J025428.94+003550.4 G 02 54 28.94 +00 35 50.4           ~ 5 0
5 SDSS J030149.01-005257.4 EmG 03 01 49.026 -00 52 57.39           ~ 12 0
6 SDSS J031301.57+001040.2 AG? 03 13 01.57 +00 10 40.3           ~ 4 0
7 [PBT2001] SBSG 0335-052 W G 03 37 38.40 -05 02 37.5   19.14     18.85 ~ 110 1
8 SBSG 0335-052B G 03 37 44.04 -05 02 40.2   16.77 16.65   16.79 ~ 220 1
9 BD+52 913 WD* 05 05 30.6180977592 +52 49 51.919301604 10.25 11.44 11.69 11.93 12.108 DA.8 1153 0
10 Z 262-28 AG? 07 47 31.944 +51 11 28.95   14.8       ~ 33 0
11 SDSS J081239.52+483645.3 bCG 08 12 39.532 +48 36 45.27           ~ 25 0
12 US 1442 Sy1 08 40 29.9112912216 +47 07 10.241384412   18.2       ~ 68 0
13 SDSS J091159.43+313535.9 AG? 09 11 59.434 +31 35 35.92           ~ 15 0
14 Mrk 116 AGN 09 34 02.1 +55 14 25           ~ 1179 1
15 LEDA 27591 SBG 09 40 12.843 +29 35 30.30   16.32 16.08     ~ 65 0
16 LEDA 28037 AG? 09 46 22.843 +54 52 08.27   16       ~ 15 0
17 Z 153-5 AG? 09 56 46.047 +28 49 43.77 14.82 14.74 14.59 14.55 26.509 ~ 252 1
18 LEDA 39402 AGN 12 17 17.093 -28 02 32.67   17       ~ 143 0
19 BD+28 4211 HS* 21 51 11.0221915656 +28 51 50.367627468 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 837 0
20 HS 2236+1344 bCG 22 38 31.1192205216 +14 00 29.770282476           ~ 38 0
21 Feige 110 HS* 23 19 58.3996844256 -05 09 56.171142864 10.360 11.45 11.50 11.970 12.145 sdO8VIIIHe5 673 1

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