1997A&A...318..931T


Query : 1997A&A...318..931T

1997A&A...318..931T - Astronomy and Astrophysics, volume 318, 931-946 (1997/2-3)

The H II/molecular cloud complex W3 revisited: imaging the radio continuum sources using multi-configuration, multi-frequency observations with the VLA.

TIEFTRUNK A.R., GAUME R.A., CLAUSSEN M.J., WILSON T.L. and JOHNSTON K.J.

Abstract (from CDS):

The HII/molecular cloud complex W3 has been imaged at 4.9GHz, 14.9GHz and 22.5GHz in the radio continuum and the H66α radio recombination line with subarcsecond angular resolution using combined multiple VLA configurations. Several hypercompact continuum sources with diameters ≤1000AU have been detected toward IRS 4 and IRS 5, reminiscent of the ``Orion Radio Zoo''. They have been imaged with a maximum angular resolution of 0.1". From the flux densities at 1.3cm, 2cm and 6cm we determine their spectral indices. The compact and ultracompact HII regions with diameters <20,000AU exhibit spectral indices α in the range -0.1 to <1.5. The gradients in spectral indices across these regions correspond to asymmetries in their radio continuum intensities as well as gradients in the densities of the surrounding molecular gas. This indicates gradients in the electron density. From a direct comparison of the continuum emission of the ionized hydrogen gas with the emission of the dense molecular gas and dust continuum, we refine the analyses of the interaction of the radio components with the molecular gas. From our H66α recombination line data we compare the radial velocities of the HII regions with those found for the molecular gas toward W3. We find linewidth and velocity gradients in the ionized gas which are indicative of expansion and turbulent flows caused by pressure gradients in the ambient neutral gas. We propose that the observed morphologies of compact and ultracompact HII regions are determined by turbulent expansion of the ionized gas into highly anisotropic and clumpy molecular gas. Thus, we believe there can be no definite prediction for the morphologies observed in HII regions with current kinematic models without considering these inhomogeneities. Furthermore, we propose that the spatial and kinematic relation of the compact, ultracompact and hypercompact radio continuum regions toward W3 is indicative of sequentially triggered star formation caused by the pressure of the expanding HII regions and the subsequent compression of the molecular gas.

Abstract Copyright:

Journal keyword(s): ISM: HII regions - ISM: clouds - ISM: individual: W 3 - ISM: kinematics and dynamics - radio lines: ISM - stars: formation

Nomenclature: Table 3: [TGC97] W3AaN (Nos 3Ma-3Mc, 3Md1-3Md2, 3Me-3Mg, 3Ca) = [WBN72] W 3 IRS NaN (Nos 5a-5c, 5d1-5d2, 5e-5g, 4a) among which (Nos 5g, 4a) added.

Simbad objects: 35

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Number of rows : 35
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 3C 48 QSO 01 37 41.2996631208 +33 09 35.080388820   16.62 16.20     ~ 2675 2
2 W 3j HII 02 25 27.32 +62 03 43.4           ~ 16 1
3 NAME W 3 SMS 3 smm 02 25 29.5 +62 06 01           ~ 11 0
4 W 3d HII 02 25 29.8 +62 06 27           ~ 36 0
5 MPCM J022530.99+620620.9 HII 02 25 31.18 +62 06 24.5           O8V-B0.5V 100 1
6 NAME W 3 SMS 2 smm 02 25 31.2 +62 06 26           ~ 10 0
7 [TGC97] W3Ca IR 02 25 31.37 +62 06 21.0           ~ 3 0
8 W 3h HII 02 25 32.00 +62 06 59.3           ~ 26 1
9 W 3g HII 02 25 32.04 +62 05 51.8           ~ 12 0
10 W 3e HII 02 25 35.1 +62 05 35           ~ 24 2
11 2MASS J02253778+6205522 Y*O 02 25 37.78776 +62 05 52.2636           O5V-O7V 14 0
12 GAL 133.71+01.22 HII 02 25 38.1 +62 05 52           ~ 75 0
13 NAME W 3 SMS 1 smm 02 25 40.3 +62 05 53           ~ 10 0
14 [WBN72] W 3 IRS 11 IR 02 25 40.4 +62 06 03           ~ 3 0
15 MPCM J022540.39+620540.1 HII 02 25 40.51 +62 05 40.7           O9V-B2V 36 0
16 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 339 0
17 [VTD2005] K3 Rad 02 25 40.6660 +62 05 52.345           ~ 9 0
18 [MWC2005] NIR 2 Rad 02 25 40.6711 +62 05 51.920           ~ 12 0
19 [TGC97] W3Mc Rad 02 25 40.720 +62 05 52.51           ~ 9 0
20 [TGC97] W3Md1 Rad 02 25 40.77 +62 05 52.4           ~ 17 0
21 [MWC2005] NIR 1 Rad 02 25 40.79 +62 05 52.6           ~ 13 0
22 [TGC97] W3Mf Rad 02 25 40.8535 +62 05 53.889           ~ 8 0
23 [TGC97] W3Me Rad 02 25 40.858 +62 05 53.83           ~ 7 0
24 2MASS J02254173+6206244 * 02 25 41.7295815504 +62 06 24.373771380           B0V-B1V 9 0
25 2MASS J02254334+6206154 Y*O 02 25 43.3302484800 +62 06 15.387396264     19.41 17.68 15.92 O8V-O9V 22 0
26 IC 1795 HII 02 25 43.5 +62 06 13           ~ 235 0
27 MPCM J022544.35+620611.7 HII 02 25 44.26 +62 06 16.2           O6.5V-O7.5V 35 0
28 W 3k HII 02 25 44.9 +62 03 41           ~ 18 1
29 2MASS J02254709+6206131 * 02 25 47.0848638600 +62 06 13.078656000           B0V-B1V 9 0
30 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 995 3
31 4C 67.05 QSO 02 28 50.0509728096 +67 21 03.034681488   19.5   18.1   ~ 240 1
32 NAME Heart Nebula HII 02 32.7 +61 27           ~ 303 1
33 3C 84 Sy2 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 3769 3
34 NAME Per Arm PoG 03 30 +45.0           ~ 1380 0
35 [TGC97] W3Mg Rad 13 13 48.30 +61 36 31.5           ~ 3 0

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2022.05.24-21:14:45

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