Unusually enriched ancient stars in the early Universe could have gained their heavy elements from nearby supernovae explosions supplementing the gas clouds from which they were born.

Stars with the heaviest elements, such as gold, platinum and uranium, are something of a conundrum in the early Universe, as they are usually only seen in later generations of stars that have had time to fuse these heavier elements in their cores. But in the outer parts of the Milky Way, which hosts ancient stars from our own Galaxy's youth, between one and two percent of the stellar inhabitants contain unusual quantities of these elements compared with 'normal' heavy elements such as iron, oxygen and carbon.

"These stars are very old; one has an age estimate of 13.2 billion years which is comparable to the age of the Universe," describes Terese Hansen of the University of Copenhagen, who adds that these stars have masses of 0.8 solar masses. Such stars are small but live long, swelling up into red giants at the ends of their lives before cooling into white dwarfs.

Hansen's colleagues had already studied abnormal stars like these over several years using the European Southern Observatory's large telescopes in Chile, and spent an additional four years following 17 stars in the northern sky with the Nordic Optical Telescope on La Palma. Hansen noted that three of the stars had clear orbital motions, and were in binary systems.

One theory of enriched stars in binary systems results from one of the stellar pair exploding, drenching its partner in layers of the heavy elements. But in the examples studied by Hansen's team, both stars are still present, so the enrichment points to a different mechanism.

"The binary system that we have found in the sample does not show sign of a supernova explosion – the secondary stars are most probably main sequence stars with masses around 0.6 solar masses – so the enrichment in heavy elements happened before the stars formed," Hansen tells Astronomy Now. "The stars have then formed from an enriched gas cloud, some in binary systems and some as single stars."

The observation therefore supports another proposed theory, that jets from early supernovae explosions of massive stars preferentially enriched some portions of nearby gas clouds, providing the seeds from which these heavy stars formed.

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

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

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 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 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