2011ApJ...730...88E

Query : 2011ApJ...730...88E

2011ApJ...730...88E - Astrophys. J., 730, 88 (2011/April-1)

The recent star formation in NGC 6822: an ultraviolet study.

EFREMOVA B.V., BIANCHI L., THILKER D.A., NEILL J.D., BURGARELLA D., WYDER T.K., MADORE B.F., REY S.-C., BARLOW T.A., CONROW T., FORSTER K., FRIEDMAN P.G., MARTIN D.C., MORRISSEY P., NEFF S.G., SCHIMINOVICH D., SEIBERT M. and SMALL T.

Abstract (from CDS):

We characterize the star formation in the low-metallicity galaxy NGC 6822 over the past few hundred million years, using GALEX far-UV (FUV, 1344-1786 Å) and near-UV (NUV, 1771-2831 Å) imaging, and ground-based Hα imaging. From the GALEX FUV image, we define 77 star-forming (SF) regions with area >860 pc2, and surface brightness ≲ 26.8 mag (AB) arcsec–2, within 0°.2 (1.7 kpc) of the center of the galaxy. We estimate the extinction by interstellar dust in each SF region from resolved photometry of the hot stars it contains: E(B - V) ranges from the minimum foreground value of 0.22 mag up to 0.66 ±0.21 mag. The integrated FUV and NUV photometry, compared with stellar population models, yields ages of the SF complexes up to a few hundred Myr, and masses from 2x102 M☉ to 1.5x106 M☉. The derived ages and masses strongly depend on the assumed type of interstellar selective extinction, which we find to vary across the galaxy. The total mass of the FUV-defined SF regions translates into an average star formation rate (SFR) of 1.4 x 10–2 M☉/yr over the past 100 Myr, and SFR = 1.0x10–2 M☉/yr in the most recent 10 Myr. The latter is in agreement with the value that we derive from the Hα luminosity, SFR = 0.008 M☉/yr. The SFR in the most recent epoch becomes higher if we add the SFR = 0.02 M☉/yr inferred from far-IR measurements, which trace star formation still embedded in dust (age ≲ a few Myr).

Abstract Copyright: ∼

Journal keyword(s): galaxies: individual: NGC 6822 - galaxies: stellar content - Local Group - stars: formation - ultraviolet: stars

VizieR on-line data: <Available at CDS (J/ApJ/730/88): table1.dat table2.dat table3.dat>

Nomenclature: Fig. 1, Table 1: [EBT2011] EB-FUV NN (Nos 1-77). Fig. 1, Table 2: [EBT2011] EB-Ha NN (Nos 1-39).

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 83

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Number of rows : 83
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 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
3 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 6226 1
4 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
5 NAME 30 Dor Nebula SFR 05 38 36.0 -69 05 11           ~ 1276 2
6 NAME LMC 2 Supergiant Shell sh 05 41 27 -69 22.4           ~ 200 0
7 M 51 Sy2 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 4565 4
8 [HKL88] 1 HII 19 44 30.7 -14 47 34           ~ 4 0
9 [HP2009] HII 16 HII 19 44 30.88 -14 48 26.3   17.88 17.48     ~ 12 0
10 [H77] HII 2 HII 19 44 31.79 -14 41 57.0   15       ~ 34 0
11 [HKL88] 2 HII 19 44 32.0 -14 44 31           ~ 4 0
12 KD D2 ISM 19 44 32.1 -14 44 42           ~ 16 0
13 [GHG91] FIR 3 PoG 19 44 32.3 -14 44 13           ~ 9 0
14 [HP2009] HII 14 HII 19 44 32.99 -14 47 31.6   18.38 17.95     ~ 11 0
15 [HKL88] 4 HII 19 44 33.6 -14 43 43           ~ 4 0
16 KD D5 HII 19 44 34.0 -14 42 32           ~ 4 0
17 MCG-02-50-003 HII 19 44 34.38 -14 42 20.3           ~ 36 0
18 [HKL88] 5 HII 19 44 37.9 -14 42 31           ~ 4 0
19 KD D7 HII 19 44 38.0 -14 51 09           ~ 12 0
20 KD D9 HII 19 44 38.0 -14 50 56           ~ 8 0
21 KD D8 HII 19 44 38.6 -14 51 51           ~ 7 0
22 [HKL88] 6 HII 19 44 39.0 -14 51 32           ~ 5 0
23 [HKL88] 7 HII 19 44 39.5 -14 51 56           ~ 4 0
24 [HKL88] 8 HII 19 44 40.4 -14 51 59           ~ 4 0
25 [HKL88] 11 HII 19 44 44.2 -14 45 50           ~ 4 0
26 [HKL88] 12 HII 19 44 44.3 -14 46 27           ~ 4 0
27 [HKL88] 13 HII 19 44 46.3 -14 43 54           ~ 4 0
28 [HKL88] 16 HII 19 44 46.7 -14 44 02           ~ 7 0
29 [HKL88] 15 HII 19 44 46.7 -14 43 43           ~ 4 0
30 [HKL88] 17 HII 19 44 46.9 -14 44 21           ~ 4 0
31 [HKL88] 20 HII 19 44 47.4 -14 44 20           ~ 4 0
32 [HKL88] 19 HII 19 44 47.4 -14 43 21           ~ 4 0
33 [HKL88] 22 HII 19 44 47.7 -14 45 33           ~ 4 0
34 [HKL88] 21 HII 19 44 47.7 -14 44 41           ~ 4 0
35 [HKL88] 23 HII 19 44 47.9 -14 46 50           ~ 4 0
36 KD D11 HII 19 44 48.4 -14 46 15           ~ 9 0
37 KD D10 HII 19 44 48.4 -14 44 18           ~ 13 0
38 [HKL88] 27 HII 19 44 48.5 -14 45 15           ~ 4 0
39 [RHH2007] NGC 6822 C HII 19 44 48.67 -14 52 26.5   17.44 16.99     ~ 10 0
40 [HKL88] 34 HII 19 44 49.0 -14 45 33           ~ 5 0
41 [HKL88] 33 HII 19 44 49.0 -14 43 55           ~ 4 0
42 [HKL88] 32 HII 19 44 49.0 -14 43 44           ~ 4 0
43 [HKL88] 36 HII 19 44 49.1 -14 44 29           ~ 5 0
44 [HKL88] 35 HII 19 44 49.1 -14 43 35           ~ 4 0
45 KD D12 Cl* 19 44 49.27 -14 43 21.2           ~ 10 0
46 [HKL88] 40 HII 19 44 49.7 -14 44 24           ~ 5 0
47 KD D13 HII 19 44 50.1 -14 52 58           ~ 6 0
48 [HKL88] 42 HII 19 44 50.1 -14 43 44           ~ 6 0
49 [HKL88] 44 HII 19 44 50.3 -14 44 11           ~ 4 0
50 KD D14 HII 19 44 50.8 -14 52 49           ~ 5 0
51 KD D15 HII 19 44 50.9 -14 52 56           ~ 5 0
52 [HKL88] 48 HII 19 44 51.2 -14 52 54           ~ 4 0
53 [H69] NGC 6822 9 HII 19 44 51.3 -14 52 49           ~ 10 0
54 KD D16 ? 19 44 51.3 -14 52 49           ~ 2 0
55 KD D17 HII 19 44 51.5 -14 52 47           ~ 5 0
56 [HKL88] 53 HII 19 44 51.8 -14 43 49           ~ 4 0
57 KD D18 HII 19 44 52.5 -14 51 58           ~ 9 0
58 [HKL88] 55 HII 19 44 52.5 -14 44 06           ~ 4 0
59 [H25] V HII 19 44 52.84 -14 43 09.8           ~ 69 0
60 KD D21 HII 19 44 53.8 -14 43 05           ~ 9 0
61 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1661 0
62 [HKL88] 66 HII 19 44 56.6 -14 47 27           ~ 4 0
63 [HKL88] 67 HII 19 44 57.2 -14 47 36           ~ 4 0
64 KD D24 HII 19 44 57.7 -14 47 23           ~ 9 0
65 [HKL88] 73 HII 19 45 00.6 -14 43 38           ~ 5 0
66 [HKL88] 77 HII 19 45 03.2 -14 43 32           ~ 4 0
67 [HKL88] 80 HII 19 45 03.8 -14 44 04           ~ 5 0
68 [HKL88] 79 HII 19 45 03.8 -14 43 55           ~ 5 0
69 [HKL88] 78 HII 19 45 03.8 -14 43 46           ~ 5 0
70 KD D26 HII 19 45 05.2 -14 43 13           ~ 55 0
71 KD D27 HII 19 45 05.8 -14 57 31           ~ 7 0
72 KD D28 HII 19 45 06.4 -14 57 11           ~ 8 0
73 [HKL88] 97 HII 19 45 10.5 -14 44 32           ~ 4 0
74 [BRC2005] V230 HII 19 45 10.68 -14 45 26.4   23.782 21.721     ~ 5 0
75 KD D30 HII 19 45 10.8 -14 48 48           ~ 11 0
76 [HKL88] 105 HII 19 45 15.4 -14 44 39           ~ 4 0
77 [H77] HII 16 HII 19 45 15.9 -14 45 29           ~ 7 0
78 [HKL88] 106 HII 19 45 16.8 -14 45 09           ~ 4 0
79 [HKL88] 107 HII 19 45 18.2 -14 45 21           ~ 4 0
80 [HKL88] 108 HII 19 45 18.9 -14 44 53           ~ 4 0
81 NGC 6922 EmG 20 29 52.9223028168 -02 11 28.156789608   14.0   14.1 13.8 ~ 37 0
82 NAME Local Group GrG ~ ~           ~ 9325 0
83 [H69] NGC 6822 6 HII ~ ~           ~ 5 0

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