1999ApJ...514..188C


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.10CEST07:53:02

1999ApJ...514..188C - Astrophys. J., 514, 188-194 (1999/March-3)

A high-resolution VLA and optical study of NGC 604.

CHURCHWELL E. and GOSS W.M.

Abstract (from CDS):

The radio structure of the supergiant H II region NGC 604 in the dwarf spiral galaxy M33 has been observed at 3.6 cm with a resolution of ∼2" (∼8 pc) down to an rms noise level of ∼15 µJy. At least six radio components can be distinguished embedded in a more extended halo. Each radio component requires ionizing photon fluxes in the range 6-44 times that of Orion A, and the entire nebula requires about 350 times that of Orion A. The rms electron densities are in the range of a few to ∼100 cm–3, and the total ionized gas mass is ∼3x106 M. Even though the photon fluxes required to maintain ionization are large, the radiation density in each radio component is substantially less than that in Orion A due to the much larger size of the radio components in NGC 604. From a comparison of radio and Hα images provided by D. Hunter, we have derived the optical depth at Hα over the face of the nebula. Visual extinctions are greatest toward the bright radio components (2.8 to 1.7 mag) and 0.5 mag over the rest of the nebula. The increased extinction toward the bright radio components implies that the dust is physically associated with these components and requires that the dust is present in the ionized gas. The dust is probably mostly leftover from the natal clouds from which the clusters formed, although some enhancement may have occurred via photoionization of accretion disks associated with the cluster stars and/or molecular cloudlets that have been overrun by the ionization front of the nebula.Subject headings:

Abstract Copyright:

Journal keyword(s): ISM: Dust, Extinction - H II regions - ISM: individual (NGC 604) - ISM: structure - radio continuum: ISM

Nomenclature: Table 1: [CG99b] NGC 604 A (Nos A-F). Text: [CG99b] Source R (Nos I-II).

Simbad objects: 22

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Number of rows : 22

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10904 1
2 IC 1613 GiC 01 04 54.2 +02 08 00   10.42 10.01 9.77   ~ 1107 2
3 M 33 GiG 01 33 50.904 +30 39 35.79 6.17 6.27 5.72     ~ 5135 1
4 [CG99b] NGC 604 F Rad 01 34 31.70 +30 47 17.4           ~ 5 0
5 [CG99b] NGC 604 D Rad 01 34 31.92 +30 47 01.2           ~ 5 0
6 NGC 604 HII 01 34 32.1 +30 47 01           ~ 544 0
7 [CG99b] NGC 604 C Rad 01 34 32.33 +30 46 58.0           ~ 6 0
8 [LBW2010] 124 SNR 01 34 33.01 +30 46 38.8           ~ 22 0
9 [CG99b] NGC 604 A Rad 01 34 33.41 +30 46 57.3           ~ 7 0
10 [CG99b] NGC 604 B Rad 01 34 33.44 +30 46 50.3           ~ 6 0
11 ChASeM33 J013435.06+304439.3 Rad 01 34 35.04 +30 44 39.2           ~ 7 0
12 [CG99b] Source II Rad 01 34 36.02 +30 44 18.5           ~ 1 0
13 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14832 1
14 M 42 HII 05 35 17.3 -05 23 28           ~ 3724 0
15 NAME Ori A MoC 05 38 -07.1           ~ 2675 0
16 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 3965 5
17 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5336 6
18 NGC 3372 HII 10 44 19.0 -59 53 21           ~ 888 2
19 NGC 3603 OpC 11 15 18.6 -61 15 26           ~ 942 1
20 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2546 2
21 W 49 SFR 19 10 20 +09 07.7           ~ 508 1
22 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1430 0

    Equat.    Gal    SGal    Ecl

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