2000A&A...357..621C


Query : 2000A&A...357..621C

2000A&A...357..621C - Astronomy and Astrophysics, volume 357, 621-636 (2000/5-2)

Internal variation of electron density in galactic HII regions.

COPETTI M.V.F., MALLMANN J.A.H., SCHMIDT A.A. and CASTANEDA H.O.

Abstract (from CDS):

A study on the internal variation of the electron density in galactic HII regions has been conducted on a sample of 15 objects of different sizes and evolutionary stages. The [SII] λ6716/λ6731 line ratio was adopted as electron density indicator. Long slit spectrophotometry of high signal-to-noise ratio with spectral dispersion of 0.75Å/pxl and spatial scale of 0.90"/pxl were obtained at different slit positions and orientations. No systematic spatial variation of electron density was detected in nearly half of the objects studied (S 255, S 257, S 271, S 285, S 301, S 305, NGC 3372 and IC 1275). They are in general the most diffuse and probably evolved objects with low mean densities in the range Ne≃20-140cm–3. The remaining objects (S 288, S 307, NGC 2579, NGC 3503, Gum 62, Gum 64a and M 20) with mean densities Ne≃80-360cm–3, have shown a statistically significant electron density dependence on position. In most of these cases, the spatial variation of density may be interpreted as a radial gradient with the density decreasing from the centre to the edges. M 20 shows a systematic non-radial variation of electron density with maximum values occurring at its prominent dark lanes. A mean filling factor of the order of φ=0.1 was found compatible with the data. Based on their density profiles, NGC 2579, Gum 62, Gum 64a and possibly NGC 3503 were indicated as candidates of showing a `champagne flow'.

Abstract Copyright:

Journal keyword(s): ISM: general - ISM: HII regions

Simbad objects: 31

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Number of rows : 31
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 SH 2-257 HII 06 12 44 +17 59.3           ~ 123 1
2 NAME SH 2-255 IRS 1 Y*O 06 12 54.0060 +17 59 22.958           ~ 342 0
3 IC 2162 HII 06 13 04.1 +17 58 44           ~ 344 2
4 IRAS 06121+1221 MIR 06 14 55.86048 +12 20 40.4088           ~ 41 0
5 SH 2-271 HII 06 15.2 +12 22           ~ 83 1
6 SH 2-285 HII 06 55 15 -00 29.9           ~ 46 0
7 IC 466 HII 07 08 37 -04 18.8           ~ 46 0
8 RAFGL 5223 Ae? 07 08 38.7905669928 -04 19 04.843454487 12.48 12.71 12.06     B0 36 0
9 GUM 5 HII 07 09.7 -18 26           ~ 5 0
10 SH 2-301 HII 07 09 54.3 -18 29 53           ~ 47 0
11 SH 2-305 HII 07 30 04.1 -18 32 13           ~ 52 0
12 SH 2-307 HII 07 35 33 -18 45.6           ~ 60 2
13 GRS G234.70 +00.90 HII 07 35.9 -18 49           ~ 9 0
14 GUM 10 HII 08 16 16.8 -35 37 58           ~ 31 0
15 BRAN 133 HII 08 18 52.9 -36 12 15           ~ 13 0
16 NGC 2579 OpC 08 20 55.3 -36 13 23           ~ 97 4
17 NAME Car II HII Region HII 10 44 47 -59 38.8           ~ 37 0
18 NGC 3372 HII 10 45 02.23 -59 41 59.8           ~ 933 2
19 * eta Car Em* 10 45 03.545808 -59 41 03.95124 6.37 7.03 6.48 4.90 4.41 OBepec 2298 0
20 NGC 3503 RNe 11 01 15.9 -59 50 39           ~ 19 1
21 Cl Pismis 17 OpC 11 01 30 -59 52.4   9.63 9.4     ~ 45 0
22 BRAN 337 HII 11 02 56.1 -59 29 16           ~ 17 0
23 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 3982 4
24 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2660 2
25 GUM 64a HII 17 20.1 -35 58           ~ 12 0
26 NGC 6334 HII 17 20 51 -36 06.9           ~ 624 0
27 SH 2-8 HII 17 21.5 -36 02           ~ 15 0
28 M 20 OpC 18 02 42 -22 58.3           ~ 413 1
29 IC 1275 HII 18 10 07.0 -23 45 42           ~ 4 0
30 NGC 6590 RNe 18 17 06 -19 51.9           ~ 21 0
31 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1474 0

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2021.12.08-04:53:43

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