2012A&A...541A.112K


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.14CET08:44:02

2012A&A...541A.112K - Astronomy and Astrophysics, volume 541A, 112-112 (2012/5-1)

Molecular chemistry and the missing mass problem in planetary nebulae.

KIMURA R.K., GRUENWALD R. and ALEMAN I.

Abstract (from CDS):

Detections of molecular lines, mainly from H2 and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H2) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass.

Abstract Copyright:

Journal keyword(s): astrochemistry - ISM: moleculess - planetary nebulae: general

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 IRC +10216 C* 09 47 57.406 +13 16 43.56     10.96     C9,5e 2105 0
2 NGC 5315 PN 13 53 56.9609674528 -66 30 50.915454108   14.58 14.40     [WO4] 291 0
3 NGC 6302 PN 17 13 44.339 -37 06 10.95   7.1 10.10     ~ 748 1
4 PN M 4-9 PN 18 14 18.41 -04 59 22.1     16.6     ~ 72 0
5 NGC 6781 PN 19 18 28.085 +06 32 19.29     11.8     ~ 245 0
6 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 825 1
7 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2302 1
8 NGC 7293 PN 22 29 38.5453078023 -20 50 13.746093105 11.894 13.158 13.524 13.689 13.898 DAO.5 883 0

    Equat.    Gal    SGal    Ecl

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2019.11.14-08:44:02

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