Peter Clegg, Professor of Astrophysics at Queen Mary & Westfield College, London, led an international team of 40 scientists who have been monitoring the material in a planetary nebula - the remnants of a star which has reached its death throes - 3,000 light-years (18 million billion miles) away from Earth.
They were surprised to find that besides carbon and oxygen, there was also water - formed by the reaction of hydrogen atoms with oxygen atoms. Such water would be useful in "seeding" newly formed planets around young stars, to set up the conditions for life.
Professor Clegg said yesterday: "It is the first discovery of interstellar water vapour, and we didn't expect to find it because the star it came from was rich in carbon. We had expected the oxygen to be grabbed by the carbon, to form carbon monoxide and dioxide."
All elements other than hydrogen are created by stars. While young, stars are fuelled by hydrogen atoms, which are crushed together in pairs at the star's centre to form helium. When the hydrogen runs out, the star's gravity "burns" helium atoms, crushing them together to form heavier elements including carbon, oxygen and iron. All the materials of Earth - including the atoms of which we consist - were once part of a star.
The compounds were discovered by the European Space Agency's Infrared Space Observatory (ISO), mounted on an orbiting satellite that was launched last November.
Healthy star fuses hydrogen atoms at its core into helium, throwing off heat and light
Dying star's core shrinks and becomes hotter, fusing helium into higher elements such as carbon, oxygen and iron
Star dies and its core materials are thrown into the galaxy. Carbon and oxygen can react with hydrogen atoms to form other compounds in interstellar space
Remains of dead star are blown through the galaxy to fertilise planets around young starsReuse content