Zobrazeno 1 - 10
of 18
pro vyhledávání: '"M. S. El-Nawawy"'
Autor:
Magdy Y. Amin, M. S. El-Nawawy
Publikováno v:
New Astronomy. 11:138-145
We have studied the chemistry of the isolated globule Barnard (B68). The chemical evolution is studied using pseudo-time-dependent and contracting models, involving pure gas-phase and gas-grain chemistry. Our results confirm the importance of grain c
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b1ba52b0f9d5cfd036e89a86c870852e
https://doi.org/10.1016/j.newast.2005.06.006
https://doi.org/10.1016/j.newast.2005.06.006
Publikováno v:
Monthly Notices of the Royal Astronomical Society. 325:881-885
We have studied the chemistry of the molecular gas in evolved planetary nebulae. Three pseudo-time-dependent gas-phase models have been constructed for dense (104–105 cm−3) and cool (T∼15 K) clumpy envelopes of the evolved nebulae NGC 6781, M4-
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::0bf074fc43edab49c8f6d4c48200a6a7
https://doi.org/10.1046/j.1365-8711.2001.04513.x
https://doi.org/10.1046/j.1365-8711.2001.04513.x
Publikováno v:
Astrophysics and Space Science. 271:245-258
We have investigated the spatial orientation of one-sided Planetary Nebulae. Most of them if not all are interacting with the interstellar medium. Seventy percent of the nebulae in our sample have inclination angles larger than 45° to the galactic p
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2d8ac6b665cf6230440a9cebabc119a9
https://doi.org/10.1023/a:1002442632274
https://doi.org/10.1023/a:1002442632274
Autor:
M. S. El-Nawawy, Magdy Y. Amin
Publikováno v:
Earth, Moon and Planets. 75:25-39
The evolution of the different chemical species are followed in a model of contracting interstellar cloud. The central density increases from n = 10 cm−3 diffuse initial cloud model to a dense cloud with central density number of n >- 105 cm−3 af
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::e50f744547a9651e9ff38b6f9828cd8e
https://doi.org/10.1007/bf00056286
https://doi.org/10.1007/bf00056286
Publikováno v:
Earth, Moon, and Planets. 69:127-140
We have constructed a chemical reaction model in a contracting interstellar cloud including 104 species which are involved in a network of 557 reactions. The chemical kinetic equations were integrated as a function of time by using gear package. The
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::8ff55536766d79f766c107dbd116e6af
https://doi.org/10.1007/bf00613095
https://doi.org/10.1007/bf00613095
Publikováno v:
Earth, Moon, and Planets. 69:113-125
We have constructed a chemical reaction system in a contracting interstellar cloud. In paper (I) we have presented the details of the physical and chemical scheme and the method of solution. The results of our chemical model produce fractional abunda
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::03376b45b279b91fc85fe3b0e84e5eb5
https://doi.org/10.1007/bf00613094
https://doi.org/10.1007/bf00613094
Publikováno v:
Earth, Moon, and Planets. 69:95-112
We have constructed a reaction system containing the chemical families of H, C, O, N, S, Si, Cl, metals (Me) and grains. A total of 104 species have been included and a network of 557 reactions has been studied. The chemical kinetic equations were in
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::47026faad67faae8223810d3dd7b0b28
https://doi.org/10.1007/bf00613093
https://doi.org/10.1007/bf00613093
Publikováno v:
Astrophysics and Space Science. 198:237-251
We have calculated the opacity as resulting from different interstellar grain models, molecules, atoms, and ions. The resulting opacities have been applied to a numerical code used to follow the thermal evolution of a contracting cloud in one dimensi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c783b8b99e1fb8a8a4d983b85db3a993
https://doi.org/10.1007/bf00644756
https://doi.org/10.1007/bf00644756
Publikováno v:
Astrophysics and Space Science. 188:109-116
We have calculated the opacity of interstellar grains in the temperature range 10–1500 K. Two composite grain models have been considered. One of them consists of silicate coated with an ice mantle and the second has a graphite core coated also wit
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2a18e93e5c8d35d7bf7d2c79e0bc36a1
https://doi.org/10.1007/bf00642927
https://doi.org/10.1007/bf00642927
Publikováno v:
Astrophysics and Space Science. 190:257-270
We have calculated the desorption rates of both physisorbed and chemisorbed ions from grain surfaces, due to the temperature increase at densities higher than 10−13 g cm−3. It has been found that physisorbed ions desorb from grain surfaces at neu
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::bfe8f191779bb1093eae95bc1edd5300
https://doi.org/10.1007/bf00644852
https://doi.org/10.1007/bf00644852