2003A&A...397..659J


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET10:29:11

2003A&A...397..659J - Astronomy and Astrophysics, volume 397, 659-666 (2003/1-2)

The chemistry of compact planetary nebulae.

JOSSELIN E. and BACHILLER R.

Abstract (from CDS):

We report high-sensitivity millimetre observations of several molecular species (13CO, HCN, HNC, CN, HCO+ and N2H+) in a sample of compact planetary nebulae. Some species such as HCO+ and CN are particularly abundant compared to envelopes around AGB stars or even interstellar clouds. We have estimated the following average values for the column densities ratios: CN/HCN∼2.6, HCO+/HCN∼0.5, and HNC/HCN∼0.4. Thus, the chemical composition of the molecular envelopes in these compact PNe appears somewhat intermediate between the composition of proto-PNe (such as CRL2688 or CRL618) and well evolved PNe (such as the Ring, M4-9, or the Helix). From observations of the CO isotopomers, we have estimated that the 12C/13C ratio is in the range 10≲12C/13C≲40. These values are below those expected from standard asymptotic giant branch models and suggest non-standard mixing processes. The observed molecular abundances are compared to very recent modelling work, and we conclude that the observations are well explained, in general terms, by time-dependent gas-phase chemical models in which the ionization rate is enhanced by several orders of magnitude with respect to the average interstellar value. Thus, our observations confirm that the chemistry in the neutral shells of PNe is essentially governed by the high energy radiation from the hot central stars. The complexity of the chemical processes is increased by numerous factors linked to the properties of the central star and the geometry and degree of clumpiness of the envelope. Several aspects of the PN chemistry that remains to be understood are discussed within the frame of the available chemical models.

Abstract Copyright:

Journal keyword(s): planetary nebulae: general - ISM: molecules

Simbad objects: 16

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Number of rows : 16

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 PN BV 1 PN 00 20 00.450 +62 59 03.16           ~ 53 0
2 PN K 3-94 PN 03 36 08.086 +60 03 46.29           ~ 42 0
3 RAFGL 618 pA* 04 42 53.6245215366 +36 06 53.397219192   16.32   12.59   C-rich 963 0
4 PN M 1-13 PN 07 21 15.037 -18 08 34.65   11.0       ~ 93 0
5 PN M 1-17 PN 07 40 22.198 -11 32 29.92           ~ 97 0
6 OH 231.8 +4.2 OH* 07 42 16.947 -14 42 50.20           M10III+A 509 1
7 IC 4406 PN 14 22 26.1443764953 -44 09 02.205426646   11.5 10.90     ~ 269 0
8 NGC 6072 PN 16 12 58.3630225774 -36 13 47.401537466     12.10     ~ 163 0
9 PN M 4-9 PN 18 14 18.41 -04 59 22.1     16.6     ~ 72 0
10 M 57 PN 18 53 35.0969571234 +33 01 44.883146221   15.405 15.769 15.901 16.062 DA(O?) 796 2
11 PN K 3-24 PN 19 12 05.88 +15 09 04.5           ~ 44 0
12 NGC 6781 PN 19 18 28.085 +06 32 19.29     11.8     ~ 249 0
13 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 837 1
14 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2353 1
15 IC 5117 PN 21 32 30.97 +44 35 47.5     16.7     ~ 291 0
16 NGC 7293 PN 22 29 38.5453078023 -20 50 13.746093105 11.894 13.158 13.524 13.689 13.898 DAO.5 907 0

    Equat.    Gal    SGal    Ecl

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2021.03.03-10:29:11

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