Astronomy and Astrophysics – Astronomy
Scientific paper
Apr 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000apj...532..994h&link_type=abstract
The Astrophysical Journal, Volume 532, Issue 2, pp. 994-1005.
Astronomy and Astrophysics
Astronomy
26
Ism: Molecules, Molecular Processes, Ism: Planetary Nebulae: Individual: Ngc Number: Ngc 7027
Scientific paper
In response to the recent molecular observations by ISO and millimeter-wave telescopes, we have developed a spherically symmetric, steady state chemical model for the planetary nebula NGC 7027. In our model, the neutral envelope consists of a geometrically thin, high-density shell of constant density and an outer stellar wind region with an inverse-square law density profile. The neutral envelope is subjected to ultraviolet (UV) radiation both from the central star and from the external interstellar field. Under an assumed visual extinction of 4 mag for the neutral envelope, the gas in our model is half molecular and half atomic. Simple molecules such as CH, CH+, OH are abundantly formed at an assumed gas temperature of 800 K in the partially molecular shell. The presence of molecular ions such as HCO+ and CO+ is well explained by photochemistry at high temperatures. The model CN/HCN ratio is almost constant at about 30 throughout the wind region and is 1-10 in the dense shell, comparable to observed values in planetary nebulae. Our model suggests that molecules are as efficiently formed with timescales shorter than 100 yr as they are photodissociated in the neutral envelope of NGC 7027 and probably in other young planetary nebulae.
Hasegawa Tatsuhiko
Kwok Sun
Volk Kevin
No associations
LandOfFree
A Chemical Model of the Neutral Envelope of the Planetary Nebula NGC 7027 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 A Chemical Model of the Neutral Envelope of the Planetary Nebula NGC 7027, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Chemical Model of the Neutral Envelope of the Planetary Nebula NGC 7027 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-750278