Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-06-11
Astrophys.J. 577 (2002) 961-973
Astronomy and Astrophysics
Astrophysics
14 pages, 4 figures, accepted in ApJ
Scientific paper
10.1086/342229
We have observed with the 30-m IRAM telescope, the CSO telescope and the ISOsatellite (Infrared Space Observatory) the rotational lines of CO at millimeter, submillimeter and far infrared wavelengths in the direction of C-rich stellar objects at different stages of evolution : CRL 2688 (a very young Proto-Planetary Nebula), CRL 618 (a Proto-Planetary Nebula), and NGC 7027 (a young Planetary Nebula). Several changes in the longwave emission of CO and other molecules are discussed here in relation with the degree of evolution of the objects. In the early stages, represented by CRL 2688, the longwave emission is dominated by CO lines. In the intermediate stage, CRL 618, very fast outflows are present which, together with the strong UV field from the central star, dissociate CO. The released atomic oxygen is seen via its atomic lines, and allows the formation of new O-bearing species, such as water and OH. The abundance of HNC is enhanced with respect to HCN as a result of the chemical processes occurring in the photo-dissociation region (PDR). At this stage, CO lines and [OI] lines are the dominant coolants, while the cooling effect of [CII] is rising. At the Planetary Nebula stage, NGC 7027, large parts of the old CO AGB material have been reprocessed. The spectrum is then dominated by atomic and ionic lines. New species such as CH+ appear. Water has probably been reprocessed in OH.
Cernicharo Jose
Goicoechea Javier R.
Herpin Fabrice
Pardo Juan Ramon
No associations
LandOfFree
Chemical Evolution of the Circumstellar Envelopes of Carbon-rich Post-AGB objects does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Chemical Evolution of the Circumstellar Envelopes of Carbon-rich Post-AGB objects, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical Evolution of the Circumstellar Envelopes of Carbon-rich Post-AGB objects will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-518414