Welcome to the homepages of the course Astrochemistry. The course is a lecture series given by Ewine F. van Dishoeck (ewine@strw.leidenuniv.nl) at Leiden Observatory in Spring of 2008.

On these pages information, recommended as well as further literature and interesting links related to that course can be found, including copies of the lecture notes as they come along. They will be maintained and updated regularly. If you have any questions or suggestions to these pages please contact Nadine Wehres(wehres@strw.leidenuniv.nl), who is also available if you have questions about the course, course material or related issues.


The space between the stars is not empty but filled with a very dilute gas with extremely low densities and temperatures, providing a unique laboratory with conditions not normally encountered on Earth. A surprisingly rich chemistry occurs in these clouds, as evidenced by the discovery of more than 130 different molecules over the last 40 years. Some of these, such as ions HCO+ and N2H+ and radicals like HCCCCCCCN, were found in space before they were identified in a laboratory on Earth. There is ample evidence for the existence of even larger molecules, in particular Polycyclic Aromatic Hydrocarbons and perhaps ionized C_60. In addition to gas-phase molecules, small 0.1 micron-sized solid particles have been found. A wealth of new information has been obtained on these grains from recent infrared observations regarding the composition of the silicates, oxides and ices. Some of the questions that will be addressed are: How are these molecules formed? Where are they found? How do their abundances differ from place to place? What are the basic molecular processes and what is the interaction between the gas and the grains?

From the astronomical perspective, molecules are excellent temperature and density probes of the dense molecular clouds in which new stars are formed. Moreover, they control the cooling of the clouds and the ability of clouds to collapse. Finally, interstellar matter forms the raw material from which new planetary systems like our own are formed. The seminars will follow the evolution of molecules from the early universe to molecular clouds and circumstellar disks around new stars and solar system material such as comets.

These pages are maintained by Nadine Wehres.
Last modified: Mon Jan 28 14:51:47 2008