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Caught in the act: the Swift satellite observes a supernova explosion in real-time

The spiral galaxy NGC 2770, where the Swift satellite observed a new supernova. Credit: NASA/Swift Science Team/Stefan Immler.

Caught in the act: the Swift satellite observes a supernova explosion in real-time

International team of scientists make the first observation of the beginnings of a supernova.

Issued on 22 May

UK astronomers are part of an international team that has used the Swift satellite to observe the first moments of a supernova explosion as it happens. The results are presented in a paper in the journal Nature today (22 May 2008) led by Dr. Alicia Soderberg of Princeton University. This extraordinarily fortunate discovery led to multiple observations with other telescopes and allowed the totality of a supernova explosion to be observed for the first time.

Dr. Kim Page of the University of Leicester, who led the X-ray analysis, said that “this observation is by far the best example of what happens when a star dies and a neutron star is born”. A typical supernova occurs when the core of a massive star runs out of nuclear fuel and collapses under its own gravity to form an ultra-dense object known as a neutron star. The newborn neutron star compresses and then rebounds, triggering a shock wave that ploughs through the star’s gaseous outer layers and blows the star to smithereens. Theoretical models have long predicted that this shock "break-out" will produce bright X-ray emission lasting a few minutes but until now the X-ray signal has never been detected.

Dr. Paul O’Brien, also from the University of Leicester, said “the X-rays from the shock break out are the earliest electromagnetic radiation that has ever been detected from a supernova. Understanding supernovae is important as these nuclear furnaces make the heavy elements from which planets like ours form.”

Until this discovery, astronomers have only found supernovae days or weeks later, when the expanding shell of debris is energized by the decay of radioactive elements forged in the explosion. Dr. Patricia Schady of the Mullard Space Science Laboratory, University College London said "Within 2 hours of the burst of X-rays we could see the expanding ultraviolet fireball with Swift. Telescopes in space and around the world were alerted well in time to see the radioactive debris as it brightened over the next few days."

The discovery of the first shock breakout can be attributed to luck and Swift's unique design. On January 9, 2008, Swift was observing a supernova known as SN 2007uy in the spiral galaxy NGC 2770, located 90 million light-years from Earth in the constellation Lynx. During this observation an extremely bright 5-minute X-ray outburst occurred in another part of NGC 2770 which was recognized as another supernova occurring while Swift looked.

In a paper to appear in the May 22 issue of Nature, Soderberg and colleagues show that the energy and pattern of the X-ray outburst are consistent with a shock wave bursting through the surface of the progenitor star. This marks the birth of the supernova now known as SN 2008D.

Although astronomers were lucky that Swift was observing NGC 2770 just at the moment when SN 2008D’s shock wave was blowing up the star, Dr. Mat Page also of the Mullard Space Science Laboratory, said “Swift is well equipped to study such an event because of its multiple instruments observing in gamma rays, X-rays, and ultraviolet light. " The X-ray camera and the Ultraviolet-Optical Telescope on Swift were built in the UK.

Professor Keith Mason, CEO of the Science and Technology Facilities Council which funds UK involvement with Swift, said “Supernova explosions are taking place all over the Universe right now, but astronomers can usually only detect them as they grow brighter after the star has started its violent death. This is a once in a lifetime moment, where Swift happened to be looking in the right area of the sky and is built to respond extremely rapidly, so could study supernova SN2008D right from the first moment it started.”

Due to the significance of the X-ray outburst, Soderberg and colleagues immediately mounted an international observing campaign to study SN 2008D. Observations were made with major telescopes such as the Hubble Space Telescope, the Chandra X-ray Observatory, the Very Large Array in New Mexico, the Gemini North telescope in Hawaii, the Keck I telescope in Hawaii, the 200-inch and 60-inch telescopes at the Palomar Observatory in California, and the 3.5-meter telescope at the Apache Point Observatory in New Mexico.

The combined observations helped pin down the energy of the initial X-ray outburst, which will help theorists better understand supernovae. The observations also show that SN 2008D is an ordinary Type Ibc supernova, which occurs when a massive, compact star explodes. Significantly, radio and X-ray observations found no evidence that a jet played a role in the explosion, ruling out a rare type of stellar explosion known as a gamma-ray burst.

Swift spends most of its time observing GRBs, but due to its agility can also observe many other objects each day. This unique capability makes Swift a particularly capable multi-wavelength observatory.

Swift is a NASA mission in collaboration with the Science Technology and Facilities Council (STFC) in the UK and the Italian Space Agency (ASI) in Italy. For more information on Swift, please visit:

Notes for Editors

UK Institutions involved in this result are: University of Leicester, University College London Mullard Space Science Laboratory and the University of Southampton.

Julia Maddock, STFC Press Office,, Tel +44 1793 442094

Dr. Kim Page, Department of Physics & Astronomy, University of Leicester, University Road, Leicester, Phone: 0116 223 1706, E-mail:

Dr. Paul O’Brien, Department of Physics & Astronomy, University of Leicester, University Road, Leicester, Phone: 0116 252 5203, E-mail:

Dr Patricia Schady, Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking RH5 6NT, Phone: 01483 204261, E-mail:

Dr Mat Page, Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking RH5 6NT, Phone: 01483 204283, E-mail:

Dr Tom Maccarone, University of Southampton,, Tel + 44 (0)238059 7548

Figures and captions:

Supernova before (with labels).

Supernova before (without labels).

NASA’s Swift satellite took these images of SN 2007uy in galaxy NGC 2770 before SN 2008D exploded. An X-ray image is on the left, the right is in visible light. Credit: NASA/Swift Science Team/Stefan Immler.

Supernova after (with labels).

Supernova after (without labels).

On January 9 Swift caught a bright X-ray burst from an exploding star. A few days later, SN 2008D appeared in visible light. Credit: NASA/Swift Science Team/Stefan Immler.


Launched in November 2004, Swift detects gamma-ray burst and X-ray flashes, and relays their coordinates to the scientific community within seconds. While SWIFT rapidly re-points to continue observations with its high resolution telescopes of the decaying X-ray, UV and optical afterglows that accompany these events, rapid follow-up observations may also be undertaken by other more powerful satellites such as Chandra, the Hubble Space Telescope or XMM satellites and by the European Southern Observatory’s Very Large Telescope [VLT] and other major observatories. These powerful co-ordinated observation programmes, instigated by SWIFT, are slowly unravelling the mystery of star explosions.

Goddard Space Flight Centre in the US manages Swift, a NASA mission with participation of the Italian Space Agency [ASI] and the Science and Technology Facilities Council [STFC] in the United Kingdom.

Swift, a medium-class Explorer mission was built in collaboration with national laboratories and universities including the Los Alamos National Laboratory, Penn State University, Sonoma State University, the University of Leicester and University College London Mullard Space Science Laboratory.

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 partnerships.

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 contributes money for the 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 2007 and 2008 we will invest approximately £678 million.

The Council is a partner in the UK space programme, coordinated by the British National Space Centre.

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