Large galaxies that were present in the first few billion years after the big bang were bloated on gas, resulting in a rash of star formation that outstripped the current rate at which stars are born in the Universe today by up to ten times.

Astronomers have known that stars formed in far higher numbers in the early Universe, and that there was a greater abundance of massive stars in the past, but until now there has never been a satisfactory understanding of why this was the case. Were star factories simply more efficient in the past, or was gas much more plentiful? New observations made with ground-breaking sensitivity at the Plateau de Bure millimetre Interferometer in the French Alps – the most powerful millimetre interferometer in the world, linking six 15m radio telescopes – have mapped both the distribution and motion of molecular hydrogen gas clouds in galaxies as far away as 10.7 billion light years (a redshift of about 2.3). Previously this had only ever been achieved in brilliantly bright quasars (galaxies with extremely active cores); to observe cold gas in normal galaxies at such a distance “has opened the door for an entirely new avenue of studying the evolution of galaxies,” says Pierre Cox of the Institute for Radio Astronomy in the Millimetre Range (IRAM).

The observations didn’t measure the cold hydrogen directly, but instead latched onto the easier-to-see emission lines from carbon monoxide molecules, which are also present within the clouds. Huge reservoirs of gas were detected, confirming that there was more gas in galaxies ten billion years ago than there is today. This gas is accumulated from cannibalisation of nearby dwarf galaxies and large amounts of intergalactic gas pulled in by the gravity of the dark matter haloes around the galaxies. The more gas there is, the more stars are born. Because stars much more massive than our Sun are only born in a ratio of one to several hundred lower mass stars, the greater star formation rate results in larger numbers of massive stars that will explode as supernovae.

“These findings provide us with clues and constraints for theoretical models that we will use to study the early phases of galaxy development in more detail,” says Andreas Burkert of the Excellence Cluster Universe at the Technische Universitaet Muenchen in Garching, Germany. “Eventually these results will help us understand the origin and the development of our Milky Way.”

Our latest 132-page Astronomy Now special edition is an extravaganza of astronomy for the year ahead, with a complete 30-page guide to observing the planets, moon, meteor showers, two solar eclipses, and the deep sky in 2010.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This special publication features the photography of British astro-imager Nik Szymanek and covers a range of photographic methods from basic to advanced. Beautiful pictures of the night sky can be obtained with a simple camera and tripod before tackling more difficult projects, such as guided astrophotography through the telescope and CCD imaging.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Explore the Universe with these new versions of the award-winning Starry Night Software. Available now from the Astronomy Now Store.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Astronomy Now is pleased to announce the publication of Exploring Mars. The very best images of Mars taken by orbiting spacecraft and NASA's Spirit and Opportunity rovers fill up the 98 glossy pages of this special edition!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This new poster features some of the best pictures from NASA's amazing Mars Exploration Rovers Spirit and Opportunity.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE