Table 4: Derived parameters from the ATCA and VLA radio continuum observations. Given are the Galactocentric and heliocentric distance, the observed frequency used in the calculations and the derived parameters: linear diameter, opacity, emission measure, electron density and number of ionizing photons required to maintain the ionization of the nebula. The IRAS luminosity is given in the last column.
          Radio properties  
Source $R_{\rm Gal}$ R $\nu$   Diameter$^\dagger$ $\tau_\nu$ EM $n_{\rm e}$ log $N_{\rm Lyc}$ $L/L_{\odot}$
  (kpc) (kpc) (GHz)   (pc)   (106 pc cm-6) (103 ${\rm cm^{-3}}$) (s-1) (104)
IRAS 01045   13.8 7.0 8.4   0.16 0.03 5.2 5.7 47.82 4.10
IRAS 10589   9.5 8.0 4.8   0.50 0.06 3.2 2.5 48.62 29.4
IRAS 11143   9.7 8.8 4.8   2.82 0.005 0.3 0.3 49.05 17.1
IRAS 12063   9.3 9.5 4.8   1.22 0.02 1.2 1.0 48.97 45.0
IRAS 12073 A 10.1 10.8 4.8   0.41 0.6 35.5 9.3   49.49 $^\triangle$ 400
... B ... ... ...   0.37 0.2 10.1 5.2 48.85 ...
IRAS 12331   6.9 4.5 4.8   1.47 0.006 0.3 0.5 48.58 8.45
IRAS 15384   6.4 2.7 4.8   0.53 0.02 1.3 1.6 48.26 10.1
IRAS 15502 A 4.5 7.0 4.8   0.16 0.7 37.5 15.3  48.68$^\star$ 131
... B ... ... ...   0.08 0.3 16.7 14.0 47.78 ...
IRAS 16128   5.5 3.7/11.4 8.6   0.32/0.98 0.05 8.8 5.2/3.0   48.65/49.63$^\lhd$ 22.8/216
IRAS 17160 A 3.0 5.7/11.0 8.6   0.62/1.20 0.01 2.2 1.9/1.3   48.63/49.21$^\square$ 35.6/133
... B ... $\natural$ ...   0.09/0.17 0.02 3.1 5.9/4.3 47.09/47.66 ...
... C ... $\natural$ ...   0.07/0.14 0.02 3.5 6.9/4.9 47.00/47.56 ...
... D ... $\natural$ ...   0.06/0.12 0.1 21.8 18.9/13.6 47.61/48.18 ...
... E ... $\natural$ ...   0.03/0.06 0.08 15.3 22.4/16.1 46.85/47.42 ...
IRAS 17221   5.2 3.4/13.4 4.8   1.10/4.35 0.005 0.3 0.5/0.3 48.25/49.44 7.52/117
IRAS 17279 A 3.4 5.1/11.8 8.6   0.49/1.14 0.003 0.6 1.1/0.7   47.88/48.61$^\boxplus$ 10.4/55.9
... B ... $\natural$ 4.8   0.07/0.15 0.1 6.3 9.7/6.4 47.15/47.88 ...
... C ... $\natural$ ...   0.08/0.19 0.09 4.8 7.6/5.0 47.23/47.96 ...
IRAS 18032 B 3.0 5.7 8.4   0.38 0.006 1.1 1.7  47.92$^\oplus$ 32.3
... C ... ... ...   0.11 0.01 2.1 4.3 47.11 ...
... D ... ... ...   0.03 0.2 31.2 33.6 47.08 ...
IRAS 18479 A 7.4 13.0 8.4   0.30 0.1 27.0 9.4  49.10$^\Diamond$ 147
... B ... ... ...   0.09 0.6 119.9 35.5 48.74 ...
IRAS 19442 core 7.7 2.0 8.4   0.01 0.08 14.6 34.8  46.45$^\rhd$ 3.39
... halo ... ... ...   0.11 0.002 0.3 1.6 ... ...
IRAS 19598   9.6 8.2 8.4   0.25 0.3 44.3 13.4 49.14 187
DR21 A 8.6 2.8 8.4   0.05 0.1 20.5 20.4 47.39 c
... B ... ... ...   0.06 0.1 21.1 18.8 47.58 ...
IRAS 23133   12.6 6.7 8.4   0.2 0.02 4.3 4.2 48.10 27.5
$^\dagger$ Diameter in pc of the sphere assumed to be representative of the source (see Sect. 4). $^\triangle$ 1049.95 photons s-1 are required to ionize the whole nebula, including the contribution of the low brightness emission. $^\star$  1048.73 photons s-1 are required to ionize both components A and B. $^\lhd$  1048.83/ 1049.80 photons s-1 result when the total 4.8 GHz flux density is considered. $^\square$  1048.97/ 1049.54 result when the total 4.8 GHz flux density integrated over the whole field is considered. $^\boxplus$  1048.32/ 1049.05 photons s-1 result when the total 4.8 GHz flux density integrated over the whole field is considered. $^\oplus$ The added contribution of the 3 components A, B and C is  1048.03 photons s-1. $^\natural$ We consider it to be located at the same distance than the IRAS source. $^\Diamond$  1049.40 photons s-1 are required to ionize the whole nebula. $^\rhd$ Lymann continuum flux required to mantain the ionization of the whole nebula. $^\flat$ The added contribution of the 2 components A and B is  1047.80 photons s-1. c No IRAS fluxes avalaible.

Source LaTeX | All tables | In the text