COol or what? Unravelling the mysteries of star formation with laboratory surface science
Astrochemistry is the study of molecules in space – where are they? how did they get there? what role they play in controlling or influencing astrophysical processes? It’s also the focus of Dr. Helen Fraser’s work – and the latest addition to the research portfolio of the Department of Physics in Strathclyde. It turns out that chemistry, and interstellar molecules in particular, are one of modern astronomy’s best tools for probing the processes of star and planet formation (see Fig. 1). Through a combination of observational spectroscopy and imaging, theoretical modelling and controlled laboratory studies, we are beginning to unlock the secrets of the cosmic chemical cauldron…
It turns out that of the 140 or so molecules that have been identified to date in interstellar space, many, including the simplest molecules such as H2, H2O, CH3OH and CO2, must be formed at the surfaces of interstellar dust, in reactions involving atoms and molecules that adsorb or ‘freeze-out’ from the gas phase. Although we can observe the infrared spectra of both the dust grains and their icy mantles, almost nothing is yet understood about the processes involved in the build up of ices in interstellar regions, nor the chemical processes that subsequently lead to the formation of the more complex organic species that are often observed in the gas phase as the ices desorb. However, with inputs from surface chemistry and physics, as well as the constraints placed on the scenarios by astronomical observations, we have been able to postulate the processes involved in the solid-state chemical evolution of star forming regions (see Fig. 2). It is these process that we are now trying to elucidate under controlled pseudo-interstellar conditions in the laboratory, feeding back our knowledge to the astronomy community, and pulling back a little further the molecular veil that currently obscures our complete understanding of star and planet formation.
