2010A&A...516A.104L


Query : 2010A&A...516A.104L

2010A&A...516A.104L - Astronomy and Astrophysics, volume 516, A104-104 (2010/6-3)

Massive star formation in Wolf-Rayet galaxies. III. Analysis of the O and WR populations.

LOPEZ-SANCHEZ A.R. and ESTEBAN C.

Abstract (from CDS):

We perform a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show a substantial population of Wolf-Rayet (WR) stars. In this paper, the third of the series, we present the analysis of the O and WR star populations within these galaxies. We study the spatial localization of the WR-rich clusters via the detection of the blue WR bump, mainly composed by the broad HeII lambda4686 line and attributed to WN stars, and the red WR bump, composed by the broad CIV lambda5808 line observed in WC stars. We perform a detailed fitting of the nebular and broad emission lines within these broad features and derive the numbers of WN, WC and O stars using (i) the standard assumption of constant WR luminosities and (ii) considering metallicity-dependent WR luminosities. We then compare our results with the predictions given by evolutionary synthesis models and with previous empirical results. We report the detection of blue WR bump in 20 regions, but the red WR bump is only detected in six. Aperture effects and the exact positioning of the slit onto the WR-rich bursts play a fundamental role in their detection. The nebular HeII lambda4686 line is detected in 21 regions; its intensity clearly decreases with increasing metallicity. We derive an empirical estimation of the WNL/(WNL+O) ratio using the intensity of the broad HeII line assuming metallicity-dependent WR luminosities. As expected, the total number of WR stars increases with increasing metallicity, but objects with 12+log(O/H)<8.2 show a rather constant WR/(WR+O) ratio. The computed WCE/WNL ratios are different than those empirically found in nearby star-forming galaxies, indicating that the observed galaxies are experiencing a strong and very short burst. Considering metallicity-dependent WR luminosities, our data agree with a Salpeter-like IMF in all regimes. We consider that the contribution of the WCE stars is not negligible at low metallicities, but deeper observations are needed to detect the red WR bump because of the decreasing of the WR luminosities with decreasing metallicity. Although available models reproduce the WR properties at high metallicities fairly well, new evolutionary synthesis models for young starbursts including all involved parameters (age, metallicity, star-formation history, IMF and WR stars properties such as metallicity-dependent WR luminosities, stellar rotation and the WR binnary channel) are absolutely needed to perform an appropriate comparison with the observational data.

Abstract Copyright:

Journal keyword(s): galaxies: starburst - galaxies: interactions - galaxies: dwarf - galaxies: abundances - galaxies: ISM - stars: Wolf-Rayet

Simbad objects: 40

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Number of rows : 40
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NGC 55 GiG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 748 2
2 IC 10 G 00 20 23.16 +59 17 34.7   13.6 9.5     ~ 1082 0
3 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12107 1
4 Mrk 960 bCG 00 48 35.430 -12 42 59.77   15.5       ~ 103 0
5 NGC 300 GiG 00 54 53.4465638304 -37 41 03.168402396 8.83 8.69 8.13 7.46   ~ 1436 2
6 NAME Scl Group GrG 01 00 06 -33 44.2           ~ 495 0
7 IC 1613 GiC 01 04 54.2 +02 08 00   10.42 10.01 9.77   ~ 1188 2
8 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 5610 1
9 IRAS F02183+0019 AGN 02 20 54.530 +00 33 24.46   16.50       ~ 58 1
10 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6564 1
11 SBSG 0335-052B G 03 37 44.04 -05 02 40.2   16.77 16.65   16.79 ~ 169 1
12 Mrk 1087 AGN 04 49 44.469 +03 20 02.67   15.49 15.04     ~ 76 1
13 HCG 31 CGG 05 01 37 -04 15.4           ~ 127 0
14 HCG 31f1 PoG 05 01 39.71 -04 16 22.2           ~ 10 0
15 HCG 31f2 PoG 05 01 40.15 -04 16 27.5           ~ 9 0
16 Mrk 5 H2G 06 42 15.9 +75 37 40   17.0       ~ 109 0
17 Mrk 1199 GiG 07 23 43.5303502320 +33 26 30.926307192   13.7 13.13     ~ 107 0
18 2MFGC 6625 EmG 08 23 54.9678898128 +28 06 21.581238276   15.5       ~ 64 0
19 ESO 495-21 bCG 08 36 15.190 -26 24 33.66 12.04 11.93 11.45 11.09 12.3 ~ 541 3
20 2MASX J08382309+6507160 SBG 08 38 23.093 +65 07 16.05     14.16     ~ 122 1
21 LEDA 26955 G 09 30 09.041 +60 28 05.37           ~ 45 0
22 Mrk 116 PaG 09 34 02.1 +55 14 25           ~ 1075 1
23 ESO 566-7 IG 09 44 58.4 -19 43 32   15.36   14.66   ~ 15 0
24 ESO 566-8 IG 09 44 59.65 -19 42 45.6   15.56   14.59   ~ 29 0
25 LEDA 28398 EmG 09 51 31.7596930512 +52 59 35.987746452   18       ~ 44 0
26 ESO 436-42 EmG 10 34 38.727 -28 34 59.80   14.44 14.41 13.26   ~ 52 0
27 MCG+06-24-038 G 10 57 47.0075966640 +36 15 38.824306272   15.5 16     ~ 40 1
28 6dFGS gJ115111.7-203557 H2G 11 51 11.7 -20 35 56   15.67   15.35   ~ 84 1
29 LEDA 39055 EmG 12 14 02.4588226248 +53 45 17.525587212   18       ~ 77 0
30 Mrk 209 bCG 12 26 16.02 +48 29 36.6   15.3       ~ 328 0
31 NGC 5113 G 13 21 22.4 +57 41 28   15.2       ~ 19 0
32 LEDA 2816050 G 13 21 22.6 +57 41 29   18.5       ~ 26 0
33 KSRWR HII-2 H2G 13 39 55.9 -31 38 24           ~ 25 0
34 NGC 5253 AGN 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33 13.47 ~ 1327 4
35 [HCG2004] NGC 5253 C 4 H2G 13 39 56.020 -31 38 27.89           ~ 32 0
36 MCG+07-29-060 QSO 14 17 01.716 +43 30 13.52   15.6       ~ 165 0
37 ESO 513-11 PaG 15 00 27.10 -26 26 57.0   15.85       ~ 52 0
38 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1512 0
39 LEDA 71605 EmG 23 30 09.7 +25 31 56   15.0       ~ 53 0
40 NAME Local Group GrG ~ ~           ~ 7904 0

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2023.02.04-00:48:37

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