Astronomers have found evidence to suggest that during the early stages of the Universe, cosmic dust - the building block for the formation of planets and life throughout the cosmos - was partially created by the gradual death of carbon stars, dispelling theories that it comes solely from stars that have exploded. They observed dust forming around a dying star in a nearby galaxy, similar to the primitive galaxies that formed soon after the big bang, giving them a fascinating glimpse back in time.
The research, which was funded by the Science and Technology Facilities Council (STFC) through a grant to Manchester University, is reported in the Jan. 16 issue of the journal Science. The study is based on observations with NASA's Spitzer Space Telescope and was carried out by an international team of astronomers.
Stars produce dust – smoke-like particles rich with carbon or oxygen - as they die. But less is known about how and what kind of dust was created in the first galaxies.
"All the elements heavier than helium were made after the Big Bang in successive generations of stars", explained team leader Albert Zijlstra from The University of Manchester's Jodrell Bank Centre for Astrophysics. "We came up with the idea of looking at nearby galaxies poor in heavier elements to get a close-up view of how stars live and die in conditions similar to those in the first galaxies."
Scientists have long debated where dust in the early Universe comes from and the most popular theory has been that supernova explosions of massive stars is the only source. Up until now, dust producing carbon stars like the one observed were not thought to have existed in early galaxies.
Gregory Sloan, from Cornell University, said "We haven't seen carbon-rich dust in this primitive an environment before. What this tells us is that carbon stars could have been pumping out dust soon after the first galaxies were born".
The dust was discovered around the carbon star MAG 29, located 280,000 light years away in a small nearby galaxy called the Sculptor Dwarf. Stars more massive than the Sun end their lives as carbon stars. In our galaxy, carbon stars are a rich source of dust.
The Sculptor Dwarf contains only 4 percent of the carbon and other heavy elements in our own galaxy, making it similar to primitive galaxies seen at the edge of the universe. Those galaxies emitted the light that we now see soon after they and the universe formed.
"While everyone is focused on the questions of how much and what kind of dust supernovae make, they may not have appreciated that carbon stars can make at least some of the dust we are seeing," Sloan said. "The more we can understand the quantity and composition of the dust, the better we can understand how stars and galaxies evolve, both in the early universe and right next door."
"Observing stars such as MAG 29 is not unlike using a time machine", Sloan added, "in which astronomers can catch glimpses of what the universe looked like billions of years ago."
"MAG 29 is exceptionally rich in hydrocarbons, similar to those that are vital components in the chemistry that eventually led to the appearance of life on earth" added Mikako Matsuura from the National University of Japan.
The study also included other scientists in the UK, USA, Japan, Australia and Belgium. It is part of a project led by Albert Zijlstra at the University of Manchester's Jodrell Bank Centre for Astrophysics.
Notes for editors
Images are available from the STFC press office
The team included Gregory Sloan of Cornell University, Mikako Matsuura of the National University of Japan, team leader Albert Zijlstra and Eric Lagadec of The University of Manchester's Jodrell Bank Centre for Astrophysics. The study was based on observations with NASA's Spitzer Space Telescope.
Contacts
Julia Short
STFC Press Office
Tel: +44 (0)1793 442 012
Email: julia.short@stfc.ac.uk
Albert Zijlstra,
Jodrell Bank Centre for Astrophysics
The University of Manchester
albert.zijlstra@manchester.ac.uk
+44 (0)161 306 3925
Eric Lagadec
Jodrell Bank Centre for Astrophysics
The University of Manchester
eric.lagadec@manchester.ac.uk
+44 (0)161 275 4145
Gregory C. Sloan
Cornell University, USA
sloan@isc.astro.cornell.edu
Science and Technology Facilities Council
The Science and Technology Facilities Council ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange.
The Council has a broad science portfolio including Astronomy, Particle Physics, Particle Astrophysics, Nuclear Physics, Space Science, Synchrotron Radiation, Neutron Sources and High Power Lasers. In addition the Council manages and operates three internationally renowned laboratories:
The Rutherford Appleton Laboratory, Oxfordshire
The Daresbury Laboratory, Cheshire
The UK Astronomy Technology Centre, Edinburgh
The Council gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Laboratory for Particle Physics (CERN), the Institute Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF), the European organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA). It also funds UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, and the MERLIN/VLBI National Facility, which includes the Lovell Telescope at Jodrell Bank Observatory.
The Council distributes public money from the Government to support scientific research. Between 2008 and 2009 we will invest approximately £787 million.
Journal
Science