by A. Léger, Polycyclic Aromatic Hydrocarbons And Astrophysics Books available in PDF, EPUB, Mobi Format. Download Polycyclic Aromatic Hydrocarbons And Astrophysics books, The near Infra-Red emission of the Interstellar Medium is a very puzzling subject. In the brightest regions, where spectroscopic observa tions are possible from the ground, several bands (3.3 - 3.4 - 6.2 - 7.7 - 8.6 - 11.3 ~m) have been observed since 1973. The absence of satisfying explanation was so obvious that they were called "Unidenti fied IR Emission Bands". The puzzle still increased when were known the first results of the general IR sky survey made by the satellite IRAS. On a large scale, the near IR emission of the Interstellar medium was expected to be very small but it was observed to be about one third of the total IR emission for our own galaxy ..• The situation has moved in 1984 when it was suggested that a class of stable organic molecules, the Polycyclic Aromatic Hydrocarbons (PAH's) could be at the origin of this near IR emission. Initially based on the required refractory character of particules that should be heated to high temperature without subliming, this hypothesis leads to a sugges tive spectroscopic similarity with the observed astronomical bands. This hypothesis is attractive and it has many implications, for ins tance, the PAHs would be the most abundant organic molecules in the universe. However, many points have to be clarified and the different consequences of this suggestion should be explored.
by , Scientific And Technical Aerospace Reports Books available in PDF, EPUB, Mobi Format. Download Scientific And Technical Aerospace Reports books, Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
by A. Bonetti, Evolution Of Interstellar Dust And Related Topics Books available in PDF, EPUB, Mobi Format. Download Evolution Of Interstellar Dust And Related Topics books, In an astronomical subject of such wide applications as interstellar dust it is to be expected that not only are there diverse opinions on its precise nature, but also diverse opinions on its influence in various astrophysical environments. At this Enrico Fermi school lecturers of the highest calibre presented their subjects and points of view to the students, so that the basic scientific controversies and methodology were accessible. In addition to questions of sources and growth, the destruction of grains was extensively discussed. A number of physical processes, such as charging and heating of grains, were also considered. Classically, and in the current context of dust problems, the optics of grains individually and in clouds has been the most critically and fully treated aspect.
by COSPAR. Plenary Meeting, Space Astronomy Books available in PDF, EPUB, Mobi Format. Download Space Astronomy books, The papers presented in this volume are taken from several meetings held during the World Space Congress. They include papers on X-ray and EUV astronomy research and results from recent space missions. A section on infrared and submillimeter astronomy also forms part of this volume.