Astrophysics Interstellar Matter

As they cool following emission from stars, the elementary species (ions and atoms) form molecules and eventually particles via homogeneous nucleation. These particles and perhaps others originating in other ways provide surfaces for heterogeneous processes facilitating or causing the formation of molecular species not possible by purely isolated molecular reactions. Particle optical interactions are partly responsible for both their dispersal in space and for stellar obscuration [1.43]. 

---

Cloud physics Comet ary Physics Cosmology Galactic Structure and Evolution Interstellar Matter Magnetic Fields in Astrophysics Radio-Astronomy INTEREEROMETRY SOLAR SYSTEM, MAGNETIC AND Electric Fields Stellar Structure and Evolution... 

A very wide range of astrophysical problems can be tackled with ISOCAM, for example - solar system studies structure of zodisM l bands and cometary trails, spectral maps of comets - interstellar matter and staff formation nature of 12 m emission of large molecules or grains, grain formation and destruction, interaction between supemovae and the interstellar medium... 

The astrochemistty of ions may be divided into topics of interstellar clouds, stellar atmospheres, planetary atmospheres and comets. There are many areas of astrophysics (stars, planetary nebulae, novae, supemovae) where highly ionized species are important, but beyond the scope of ion chemistry . (Still, molecules, including H2O, are observed in solar spectra [155] and a surprise in the study of Supernova 1987A was the identification of molecular species, CO, SiO and possibly ITf[156. 157]. ) In the early universe, after expansion had cooled matter to the point that molecules could fonn, the small fraction of positive and negative ions that remained was crucial to the fomiation of molecules, for example [156]... 

There has been particular interest in the chemistry of small organosilicon ions and their neutral counterparts for a number of reasons (i) Small SiCvHv molecules are well suited to draw analogies between the structural chemistry of silicon and carbon—or to state differences, (ii) The chemistry of small silicon compounds is viewed as fundamental in astrophysics and astrochemistry, and a large number of cationic and neutral SiRv molecules have been detected in interstellar and circumstellar matter. 

Boron is one of the three light elements (Li, Be, B) that are not effectively synthesized by nuclear reactions in stable stars. Its origin in nature must be sought in other astrophysical processes. These involve cosmic-ray collisions with interstellar atoms and neutrino-burst nucleosynthesis in supernova matter. Transient production at the solar center of one of its radioactive isotopes, however, produces energetic neutrinos that have been the easiest of the solar neutrinos to detect. 

---