2017MNRAS.472.2608S

Query : 2017MNRAS.472.2608S

2017MNRAS.472.2608S - Mon. Not. R. Astron. Soc., 472, 2608-2632 (2017/December-2)

Ultraviolet spectra of extreme nearby star-forming regions - approaching a local reference sample for JWST.

SENCHYNA P., STARK D.P., VIDAL-GARCIA A., CHEVALLARD J., CHARLOT S., MAINALI R., JONES T., WOFFORD A., FELTRE A. and GUTKIN J.

Abstract (from CDS):

Nearby dwarf galaxies provide a unique laboratory in which to test stellar population models below Z☉/2. Such tests are particularly important for interpreting the surprising high-ionization ultraviolet (UV) line emission detected at z > 6 in recent years. We present HST/COS UV spectra of 10 nearby metal-poor star-forming galaxies selected to show He II emission in SDSS optical spectra. The targets span nearly a dex in gas-phase oxygen abundance (7.8 < 12 + log O/H < 8.5) and present uniformly large specific star formation rates (sSFR ∼102 Gyr–1). The UV spectra confirm that metal-poor stellar populations can power extreme nebular emission in high-ionization UV lines, reaching C III] equivalent widths comparable to those seen in systems at z ∼ 6-7. Our data reveal a marked transition in UV spectral properties with decreasing metallicity, with systems below 12 + log O/H <= 8.0 (Z/Z☉ <= 1/5) presenting minimal stellar wind features and prominent nebular emission in He II and C IV. This is consistent with nearly an order of magnitude increase in ionizing photon production beyond the He+-ionizing edge relative to H-ionizing flux as metallicity decreases below a fifth solar, well in excess of standard stellar population synthesis predictions. Our results suggest that often-neglected sources of energetic radiation such as stripped binary products and very massive O-stars produce a sharper change in the ionizing spectrum with decreasing metallicity than expected. Consequently, nebular emission in C IV and He II powered by these stars may provide useful metallicity constraints in the reionization era.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): stars: massive - galaxies: evolution - galaxies: stellar content - ultraviolet: galaxies - ultraviolet: galaxies

Simbad objects: 70

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Number of rows : 70
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 IC 1586 bCG 00 47 56.301 +22 22 22.51   15.0       ~ 77 0
2 MCG-02-03-019 bCG 00 48 35.430 -12 42 59.77   15.5       ~ 109 0
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
4 NAME SMC Bar PoG 01 05 -72.6           ~ 264 0
5 LHA 115-N 88A HII 01 24 07.823 -73 09 03.77   13.25 12.18     ~ 83 1
6 IC 214 AGN 02 14 05.53344 +05 10 23.8692   14.4       ~ 157 0
7 SBSG 0335-052 AGN 03 37 44.06 -05 02 40.2     16.65     ~ 500 1
8 EGGR 29 WD* 04 09 28.9040081904 +17 07 54.395653512 14.66 15.378 15.323 15.408 15.515 DA3.2 134 0
9 NGC 1569 rG 04 30 49.186 +64 50 52.52 11.72 11.86 11.03     ~ 1297 3
10 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
11 RMC 136 Cl* 05 38 42.396 -69 06 03.36   5.81 5.40     ~ 2236 2
12 NGC 2363A HII 07 28 42.8 +69 11 21           ~ 588 3
13 [S75b] NGC 2403 7 HII 07 36 28.6 +65 33 49           ~ 12 0
14 HK NGC 2403 270 Cl* 07 36 52.13 +65 36 48.5           ~ 24 0
15 [S75b] NGC 2403 2 HII 07 37 06.82 +65 36 38.7           ~ 41 0
16 Mrk 116A H2G 09 34 01.9716600456 +55 14 27.789835056           ~ 46 0
17 Mrk 116 AGN 09 34 02.1 +55 14 25           ~ 1179 1
18 Mrk 116B EmG 09 34 02.389 +55 14 23.14           ~ 62 0
19 LEDA 3531560 H2G 09 42 52.7793523872 +35 47 25.800078660           ~ 26 0
20 [BKD2008] WR 245 H2G 09 42 56.7607222299 +09 28 15.872933327           ~ 13 0
21 Z 63-48 GiG 09 42 58.193 +09 28 15.64   13.7       ~ 59 0
22 Z 7-25 Sy1 09 44 01.8742171440 -00 38 31.993352700   15.5       ~ 89 0
23 GD 108 HS* 10 00 47.2462375824 -07 33 30.773994012 12.406 13.349 13.563 13.662 13.781 sdB 150 1
24 NGC 3125 AGN 10 06 33.318 -29 56 07.32 13.03 13.45 13.00 12.50 13.4 ~ 253 2
25 Z 290-12 G 10 11 51.4994549064 +58 53 23.933986224   15.7       ~ 25 0
26 [ITS2007] 52319-575-521 EmG 10 24 29.249 +05 24 51.00           ~ 30 0
27 Feige 34 HS* 10 39 36.7358839104 +43 06 09.212615280 9.613 10.91 11.14 11.319 11.464 sdOp 731 0
28 NGC 3690 IG 11 28 31.0 +58 33 41   13.19 12.86     ~ 1015 4
29 LEDA 35380 EmG 11 29 14.1694027224 +20 34 52.192200756   16.38   15.55   ~ 51 0
30 IC 700 GiG 11 29 15.3001498104 +20 34 59.400213672   14.16   13.94   ~ 50 0
31 Z 127-57 EmG 11 48 27.3422096304 +25 46 11.585848764   15.0       ~ 35 0
32 Mrk 193 H2G 11 55 28.34 +57 39 52.0   16.5       ~ 63 0
33 [ITS2007] 52790-1313-423 EmG 11 55 28.3515242280 +57 39 51.677013060           ~ 12 0
34 LEDA 37578 Sy1 11 57 12.4477194312 +02 28 28.039855080   18       ~ 39 0
35 NGC 4204 GiC 12 15 14.359 +20 39 32.68   14.3       ~ 162 0
36 Mrk 1315 H2G 12 15 18.5915257128 +20 38 26.666992356   16.5       ~ 57 0
37 NGC 4228 SBG 12 15 39.174 +36 19 36.80 10.63 10.30 9.93 9.74   ~ 1017 1
38 LEDA 39402 AGN 12 17 17.093 -28 02 32.67   17       ~ 143 0
39 SDSSCGB 20312.2 H2G 12 22 25.7950077216 +04 34 04.768689612           ~ 7 0
40 NGC 4301 GiG 12 22 27.246 +04 33 58.69   13.40 12.99     ~ 126 1
41 NAME Virgo Cluster ClG 12 30 47.8 +12 23 07           ~ 7107 0
42 RMB 132 bCG 12 30 48.6089418912 +12 02 42.805457196     16.78   16.44 ~ 102 0
43 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7815 3
44 BD+25 2534 HS* 12 37 23.5161671712 +25 03 59.867922240 9.117 10.26 10.59 10.642 10.809 sdB1(k) 268 0
45 IC 3639 Sy1 12 40 52.8344884344 -36 45 21.057011172   13.01 13.50 11.87 12.7 ~ 262 1
46 NGC 4670 AG? 12 45 17.150 +27 07 31.76   12.6 12.90     ~ 271 0
47 NGC 4861 H2G 12 59 02.340 +34 51 33.98   12.90 12.32     ~ 389 2
48 LEDA 45394 EmG 13 06 42.43 -12 04 22.2           ~ 31 0
49 LEDA 45456 EmO 13 07 24.7 -13 10 42           ~ 8 0
50 M 63 LIN 13 15 49.2741893928 +42 01 45.728076108   9.34 8.59 8.35   ~ 1292 2
51 MCG+10-19-072 Sy2 13 25 53.82030 +57 15 16.0664   15.0       ~ 84 0
52 [DAZ2013] 38 Cl* 13 39 55.53 -31 38 29.7           ~ 18 0
53 NGC 5253A H2G 13 39 55.9 -31 38 24           ~ 26 0
54 [DAZ2013] 129 Cl* 13 39 55.98 -31 38 31.9           ~ 23 0
55 NGC 5253 rG 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33 13.47 ~ 1421 4
56 NGC 5253B H2G 13 39 56.00 -31 38 25.8           ~ 18 0
57 NGC 5253C H2G 13 39 56.020 -31 38 27.89           ~ 33 0
58 2MASX J13482230-4221138 H2G 13 48 22.2996191952 -42 21 14.086526796   17       ~ 38 0
59 LEDA 50039 G 14 02 58.4 -30 14 15   18       ~ 12 0
60 NGC 5455 H2G 14 03 01.17 +54 14 29.4           ~ 105 0
61 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 3138 2
62 NGC 5471 EmG 14 04 28.627 +54 23 52.84           ~ 250 1
63 Z 219-66 QSO 14 17 01.716 +43 30 13.52   15.6       ~ 181 0
64 NAME EGS-zs8-1 G 14 20 34.893 +53 00 15.33           ~ 42 0
65 LEDA 140535 AGN 15 45 43.5456237456 +08 58 01.398139032     16.0     ~ 56 0
66 NGC 6090 PaG 16 11 40.3 +52 27 21   14.0       ~ 446 1
67 Z 251-43 bCG 16 48 24.1208837112 +48 42 32.756012676   14.6       ~ 48 0
68 ESO 338-4 EmG 19 27 58.338 -41 34 30.81   13.55 13.21 13.14 13.43 ~ 253 1
69 NGC 7552 Sy1 23 16 10.66 -42 35 04.7 11.34 11.22 10.57 10.08 11.1 ~ 574 3
70 NAME Local Group GrG ~ ~           ~ 9325 0

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