Stars 'r' us! The cosmic chemical connection

Stars r us The surface science facility at the Central Laser Facility, Rutherford Appleton Laboratories, UK. The experiments used to recreate the conditions in interstellar space and investigate the chemistry occurring there are extremely complex, expensive and sizeable.

'We are all made of stars', the title of Moby's 2002 single, is a statement that represents the truth. The atoms that make up our bodies originated in stars. Chemical reactions between gases and dust in space lead to increasingly complex molecules that influence conditions during star formation, and are the building blocks for planets and possibly life. How these chemical reactions occur in cold, dark space is being uncovered by astrochemistry, a scientific field that combines the work of astronomers and chemists. 'By recreating the extreme conditions of space in the laboratory, using powerful telescopes to observe stars and clouds of gas and dust in our own galaxy, and then combining the results in computer modelling, scientists have started to answer the big question of how stars, planets and life are made,' says Helen Fraser of the Department of Physics, University of Strathclyde.

At the heart of this research is spectroscopy, a technique that can identify the molecules that, even at vast distances from Earth, are found around stars and in the clouds of gas and dust in which stars are born. Every molecule absorbs or reflects electromagnetic radiation in a characteristic way, giving it a recognisable fingerprint', explains Helen. Powerful telescopes such as the European Southern Observatory's Very Large Telescope in Chile and NASA's Spitzer space telescope are used to record these fingerprint spectra by looking for the heat energy, or infrared radiation being emitted by warm' dust deep inside the star-forming clouds.

When molecules lie between the path of the telescope and the cloud they absorb heat energy, and start madly vibrating, giving a characteristic fingerprint shouting out that they are present', explains Helen. To date, 212 different molecular species have been detected in space from molecular hydrogen to complex molecules containing 12 or more atoms.

Spitzer, launched in 2003, detects infrared radiation enabling scientists to see' star forming regions hidden from the naked eye and visible telescopes by dust scattering the light, like a cloud blocks out the Sun. Using the infrared, Spitzer has uncovered hundreds of baby stars that will eventually end up similar to the Sun. Around these baby stars are many more complex organic species and molecules than expected.

Ammonia, made up of nitrogen and hydrogen, varies much more wildly in its abundance than we thought, and since nitrogen is closely linked to the formation of life this finding could be significant to which star systems do and don't have the potential to create life', says Helen.

Planets form from the residual gas and dust that circulates a newly created star.