2001A&A...366..439K


Query : 2001A&A...366..439K

2001A&A...366..439K - Astronomy and Astrophysics, volume 366, 439-450 (2001/2-1)

Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714.

KOTILAINEN J.K., REUNANEN J., LAINE S. and RYDER S.D.

Abstract (from CDS):

We present high spatial resolution (∼0.6)" near-infrared broad-band JHK images and Brγ 2.1661µm and H2 1-0 S(1) 2.122µm emission line images of the nuclear regions in the interacting starburst galaxies NGC 520, NGC 1614 and NGC 7714. The near-infrared emission line and radio morphologies are in general agreement, although there are differences in details. In NGC 1614, we detect a nuclear double structure in Brγ, in agreement with the radio double structure. We derive average extinctions of AK=0.41 and AK=0.18 toward the nuclear regions of NGC 1614 and NGC 7714, respectively. For NGC 520, the extinction is much higher, AK=1.2-1.6. The observed H2/Brγ ratios indicate that the main excitation mechanism of the molecular gas is fluorescence by intense UV radiation from clusters of hot young stars, while shock excitation can be ruled out. The starburst regions in all galaxies exhibit small Brγ equivalent widths. Assuming a constant star formation model, even with a lowered upper mass cutoff of Mu=30M, results in rather old ages (10-40Myr), in disagreement with the clumpy near-infrared morphologies. We prefer a model of an instantaneous burst of star formation with Mu=100M, occurring ∼6-7Myr ago, in agreement with previous determinations and with the detection of W-R features in NGC 1614 and NGC 7714. Finally, we note a possible systematic difference in the amount of hot molecular gas between starburst and Seyfert galaxies.

Abstract Copyright:

Journal keyword(s): galaxies: individual: NGC 520 - galaxies: individual: NGC 1614 - galaxies: individual: NGC 7714 - galaxies: starburst - infrared: galaxies - stars: formation

Nomenclature: Table 1: [KRL2001b] NGC 520 W (Nos C, W, E), [KRL2001b] NGC 1614 WW (Nos SE, NW), [KRL2001b] NGC 7714 N (Nos 1-4).

Simbad objects: 13

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Number of rows : 13
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 NGC 520 AG? 01 24 34.90 +03 47 29.4 12.41 12.24 11.42     ~ 514 3
2 NGC 1097 LIN 02 46 19.059 -30 16 29.68 10.46 9.97 9.48 8.72 9.8 ~ 1344 3
3 NGC 1614 Sy1 04 34 00.027 -08 34 44.57   14.66 13.99     ~ 669 0
4 NGC 3079 Sy2 10 01 57.8789863992 +55 40 47.449758324 11.57 11.54 10.86     ~ 1393 3
5 NGC 3227 Sy1 10 23 30.5765149296 +19 51 54.282206700   12.61 11.79     ~ 1709 1
6 NGC 6574 GiG 18 11 51.2465713056 +14 58 54.747570108   12.5       ~ 179 0
7 NGC 7714 GiP 23 36 14.1257730600 +02 09 18.197422668   14.91 14.36     ~ 765 1
8 APG 284 PaG 23 36 19 +02 09.3   12.6       ~ 607 0
9 NGC 7715 GiP 23 36 21.768 +02 09 25.30   11.81 12.14     ~ 138 0
10 NGC 7771 GiG 23 51 24.880 +20 06 42.57 13.42 13.08 12.25     ~ 339 4
11 [GPD95] C HII ~ ~           ~ 9 0
12 [GPD95] B HII ~ ~           ~ 9 0
13 [GPD95] A HII ~ ~           ~ 11 0

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