2005A&A...431..523B


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.01CET08:57:58

2005A&A...431..523B - Astronomy and Astrophysics, volume 431, 523-538 (2005/2-4)

Physical conditions in Photo-Dissociation Regions around Planetary Nebulae.

BERNARD-SALAS J. and TIELENS A.G.G.M.

Abstract (from CDS):

We present observations of the infrared fine-structure lines of [SiII] (34.8µm), [OI] (63.2 and 145.5µm) and [CII] (157.7µm) obtained with the ISO SWS and LWS spectrographs of nine Planetary Nebulae (PNe). These lines originate in the Photo-Dissociation Regions (PDRs) associated with the nebulae and provide useful information on the evolution and excitation conditions of the ejected material in these regions. In order to interpret the observations, the measured line intensities have been compared with those predicted by photo-dissociation models. This comparison has been done taking into account the C/O content in the nebulae. The densities derived with this comparison show a large scatter for some nebulae, probably because the density is higher than the critical density. Therefore, they are no longer sensitive to this parameter implying that transitions from other species with higher critical density should be used. The possible contribution of shocks to the observed emission characteristics of these PNe is briefly discussed and it is shown that the radiation field is the main driving force responsible for the atomic lines in the PNe that have been studied. In addition, data on the pure rotational lines of H2 in three nebulae (NGC 7027, NGC 6302 and Hb 5) are also presented. Assuming local thermal equilibrium the rotational temperature and densities have been derived. We have derived the mass of atomic gas in the PDR associated with these PNe and compared those to ionic masses derived from Hβ and molecular masses derived from low J CO observations. This comparison shows that for these nebulae, the PDR is the main reservoir of gas surrounding these objects. A comparison of the results of these evolved PNe with very young PNe from the literature suggests that as the nebula ages the relative amount of ionic gas increases at the expense of the atomic and molecular mass.

Abstract Copyright:

Journal keyword(s): ISM: lines and bands - ISM: atoms - ISM: molecules - ISM: planetary nebulae: general

VizieR on-line data: <Available at CDS (J/A+A/431/523): table1.dat>

Simbad objects: 19

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Number of rows : 19

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 RAFGL 618 pA* 04 42 53.6245215366 +36 06 53.397219192   16.32   12.59   C-rich 962 0
2 NGC 3132 PN 10 07 01.7655812249 -40 26 11.138949314   10.14 10.01     A2V 374 1
3 NGC 3139 G 10 10 05.2100042143 -11 46 41.375474998   14.24       ~ 18 0
4 NGC 3918 PN 11 50 17.7723407998 -57 10 57.059135256   10.0 8.5     ~ 365 0
5 IC 4406 PN 14 22 26.1443764953 -44 09 02.205426646   11.5 10.90     ~ 269 0
6 NGC 6072 PN 16 12 58.3630225774 -36 13 47.401537466     12.10     ~ 163 0
7 PN Mz 3 PN 16 17 13.3911453557 -51 59 10.706640574   10.8 14.00     O9.5 335 0
8 PN M 2-9 PN 17 05 37.952 -10 08 34.58   12.59 14.7     Be 507 0
9 NGC 6302 PN 17 13 44.339 -37 06 10.95   7.1 10.10     ~ 761 1
10 PN Hb 5 PN 17 47 56.20 -29 59 39.6   10.50 10.78     ~ 253 0
11 NGC 6543 PN 17 58 33.4042519454 +66 37 58.748961810   11.09 11.28     [WC] 1128 1
12 M 57 PN 18 53 35.0969571234 +33 01 44.883146221   15.405 15.769 15.901 16.062 DA(O?) 796 2
13 PN K 3-17 PN 18 56 18.164 +07 07 25.88           ~ 60 1
14 NGC 6781 PN 19 18 28.085 +06 32 19.29     11.8     ~ 249 0
15 HD 184738 PN 19 34 45.2337512278 +30 30 58.951476338   10.41 10.44     [WC9] 925 0
16 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2352 1
17 [D75b] Em* 21-021 PN 21 29 58.4712776885 +51 04 00.323547316   15.66 14.20 13.89   O7(f)/[WC11] 229 0
18 IC 5117 PN 21 32 30.97 +44 35 47.5     16.7     ~ 291 0
19 PN Hb 12 PN 23 26 14.8207203464 +58 10 54.538636094   13.51 11.49 12.44   Oe 316 0

    Equat.    Gal    SGal    Ecl

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