Double explosion heralds the death of a very massive star
A unique discovery of two celestial explosions at exactly the same position in
the sky has led astronomers to suggest they have witnessed the death of one of
the most massive stars that can exist. A global collaboration of astronomers,
led by Queen's University Belfast teamed up with Japanese supernova hunter
Koichi Itagaki to report an amazing new discovery in Nature this week (June
14th). This is the first time such a double explosion has been observed and
challenges our understanding of star-deaths.
In 2004 Koichi Itagaki discovered an exploding star in the galaxy UGC4904 (78
million light years away in the Lynx constellation), which rapidly faded from
view in the space of 10 days. It was never formally announced to the community,
but then he then found a new much brighter explosion in the same place only two years later in
2006, which he proposed as new supernova. Queen's astronomers Prof. Stephen
Smartt and Dr. Andrea Pastorello immediately realised the implications of
finding two explosions at the same position on the sky.
They began observing the 2006 supernova (named SN2006jc) with a wide range of
large telescopes and analysed Itagaki's images to show that the two explosions
were exactly in the same place. The most likely explanation for the 2004
explosion was probably an outburst of a very massive star like Eta-Carinae,
which was observed to have a similar giant outburst in the 1850s. The 2006
supernova was the final death of the same star.
Dr. Pastorello said "We knew the 2004 explosion could be a giant outburst of
very massive star, and we know that only the most massive stars can produce this
type of outburst. So the 2006 supernova must have been the death of the same
star, possibly a star 50 to 100 times more massive than the Sun. And it turns out that
SN2006jc is a very weird supernova - unusually rich in the chemical element helium
which supports our idea of a massive star outburst then death."
Dr. Pastorello used UK telescopes on La Palma (the Liverpool Telescope, and
William Herschel Telescope) in a combined European and Asian effort to monitor
the energetics of SN2006jc. He showed that the exploding star must have been a
Wolf-Rayet star, which are the carbon-oxygen remains of originally very high
mass stars.
Prof Smartt is funded by a prestigious EURYI fellowship to study the birth and
death of stars. He said "The supernova was the explosion of a massive star that
had lost its outer atmosphere, probably in a serious of minor explosions like
the one Koichi found in 2004. The star was so massive it probably formed a black
hole as it collapsed. This is the first time two explosions of the same star
have been found, and it challenges our theories of the way stars live and die. "
Although this is the first time two such explosions have been found to be coincident,
they could be more frequent than currently thought. The future Pan-STARRS project,
a new telescope with the world's largest
digital camera which can survey the whole sky once a week could search for these
peculiar supernovae. Queen's are partners in the Pan-STARRS science team and
hope to use it to understand how the most massive stars in the Universe die.
The Science and Technology Facilities Council funds UK research in astronomy and
access to telescopes such as the William Herschel Telescope.
Notes for Editors
Suggested Graphics:
http://hubblesite.org/newscenter/archive/releases/1996/23/image/a/format/large_w
eb/
Caption: This is an image of Eta-Carina in our galaxy, taken with the Hubble
Space Telescope. The star that exploded in 2004 and 2006 in the far off galaxy
2006 was likely a very massive star like Eta-Carina, of up to 100 solar masses,
and doomed to death when its core collapsed to a black hole. Credit: NASA/ESA
Hubble Space Telescope and Jon Morse
The Great Carina Nebula (NGC 3372), famous star-forming region of the southern sky. The
image spans about 40 light-years within the larger Carina Nebula at an estimated
distance of 7,500 light-years. The Carina Nebula is home to young, extremely
massive stars, including Eta Carinae, a star with well over 100 times the mass
of the Sun. Highlighted by diffraction spikes, Eta is just above and right
(east) of the Keyhole. Credit: Brad Moore
Animation and Artist's impressions
http://www-dapnia.cea.fr/Sap/Actualites/Breves/bobi070531/page_images_gb.shtml
Credit (c) Frederic Durillon - www.animea.com, Courtesy Service
d'Astrophysique/CEA
Contacts:
Julia Maddock
Science and Technology Facilities Council Press Office Tel +44-1793 442094
Julia.maddock@stfc.ac.uk
Prof. Stephen Smartt
s.smartt@qub.ac.uk
Astrophysics Research Centre, School of Maths and Physics Queen's University
Belfast
Work: 02890 971245 Home: 02890 962471 Mobile:07876014103
Dr. Andrea Pastorello
a.pastorello@qub.ac.uk
Astrophysics Research Centre, School of Maths and Physics Queen's University Belfast
Work: 02890 97 3509 Mobile: 07990964240
Partner Press Releases:
http://www-dapnia.cea.fr/Sap/Actualites/Breves/bobi070531/
http://www.inaf.it/ufficio-stampa/comunicati-stampa-del-2007/CS_16_140607
Paper details
Title: A giant outburst two years before the core-collapse of a massive star
Authors: A. Pastorell, S. J. Smartt, S. Mattila, J. J. Eldridge, D. Young, K.
Itagaki, H. Yamaoka, H. Navasardyan, S. Valenti, F. Patat, I. Agnoletto, T.
Augusteijn, S. Benetti, E. Cappellaro, T. Boles, J.-M. Bonnet-Bidaud, M.T.
Botticella, F. Bufano, C. Cao, J. Deng, M. Dennefeld, N. Elias-Rosa, A.
Harutyunyan, F. P. Keenan, T. Iijima, V. Lorenzi, P. A. Mazzali, X. Meng, S.
Nakano, T.B. Nielsen, J. V. Smoker, V. Stanishev, M. Turatto, D. Xu, L.
Zampierio
Preprint: http://uk.arxiv.org/abs/astro-ph/0703663
About the Liverpool Telescope
The Liverpool Telescope, with a two metre mirror, is a fully robotic
astronomical telescope owned and operated by the Astrophysics Research Institute of Liverpool John Moores
University in north-west England. It is the most advanced telescope of its kind
in the world, operating completely autonomously, independent of human control.
The telescope is a specialist instrument for the study of time-variable
astronomical phenomena.
The telescope was designed and built by Telescope Technologies Limited, a
spin-off company of the University.
About the William Herschel Telescope
The William Herschel Telescope is one of the telescopes of the Isaac Newton
Group (ING). The ING is owned and operated jointly by the Science and Technology
Facilities Council of the United Kingdom, the Nederlandse Organisatie voor
Wetenschappelijk Onderzoek (NWO) of the Netherlands and the Instituto de
Astrofísica de Canarias (IAC) of Spain. The telescopes are located in the
Spanish Observatorio del Roque de Los Muchachos on La Palma, Canary Islands
which is operated by the Instituto de Astrofísica de Canarias (IAC).
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 will manage and
operate 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.
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