@article{6fa58b90914c4c59948d7261e801747c,
title = "Supernova 2007bi as a pair-instability explosion",
abstract = "Stars with initial masses such that 10 M initial 100, where is the solar mass, fuse progressively heavier elements in their centres, until the core is inert iron. The core then gravitationally collapses to a neutron star or a black hole, leading to an explosionan iron-core-collapse supernova. By contrast, extremely massive stars with M initial 140 (if such exist) develop oxygen cores with masses, M core, that exceed 50, where high temperatures are reached at relatively low densities. Conversion of energetic, pressure-supporting photons into electron-positron pairs occurs before oxygen ignition and leads to a violent contraction which triggers a nuclear explosion that unbinds the star in a pair-instability supernova. Transitional objects with 100 M initial 140 may end up as iron-core-collapse supernovae following violent mass ejections, perhaps as a result of brief episodes of pair instability, and may already have been identified. Here we report observations of supernova SN 2007bi, a luminous, slowly evolving object located within a dwarf galaxy. We estimate the exploding core mass to be M core 100, in which case theory unambiguously predicts a pair-instability supernova. We show that 3 of radioactive 56 Ni was synthesized during the explosion and that our observations are well fitted by models of pair-instability supernovae. This indicates that nearby dwarf galaxies probably host extremely massive stars, above the apparent Galactic stellar mass limit, which perhaps result from processes similar to those that created the first stars in the Universe.",
author = "Avishay Gal-Yam and P. Mazzali and Ofek, {E. O.} and Nugent, {P. E.} and Kulkarni, {S. R.} and Kasliwal, {M. M.} and Quimby, {R. M.} and Filippenko, {A. V.} and Cenko, {S. B.} and R. Chornock and R. Waldman and D. Kasen and M. Sullivan and Beshore, {E. C.} and Drake, {A. J.} and Thomas, {R. C.} and Bloom, {J. S.} and D. Poznanski and Miller, {A. A.} and Foley, {R. J.} and Silverman, {J. M.} and I. Arcavi and Ellis, {R. S.} and J. Deng",
note = "Funding Information: Acknowledgements We gratefully acknowledge advice and help from E. Pian and discussions with Z. Barkat, E. Livne, E. Nakar, N. Langer and P. Podsiadlowski. This work benefited from useful interaction during the Fireworks meetings held at the Weizmann Institute (2008) and at the University of Bonn (2009). Work related to the CSS data reported here was supported by the US National Aeronautics and Space Administration (NASA) under a grant issued through the Science Mission Directorate Near-Earth Object Observations program. The joint work of A.G.-Y. and P.M. is supported by a Weizmann-Minerva grant. A.G.-Y. acknowledges support from the Israeli Science Foundation, a European Union Seventh Framework Programme Marie Curie IRG fellowship, the Benoziyo Center for Astrophysics, a research grant from the Peter and Patricia Gruber Awards, and the William Z. and Eda Bess Novick New Scientists Fund at the Weizmann Institute. P.E.N. is supported by the US Department of Energy{\textquoteright}s Scientific Discovery through Advanced Computing programme. The A.V.F. group at the University of California, Berkeley is grateful for financial support from the US National Science Foundation, the US Department of Energy, the TABASGO Foundation, Gary and Cynthia Bengier, and the Richard and Rhoda Goldman Fund. J.D. is supported by the National Natural Science Foundation of China and by the Chinese 973 Program. This work is based in part on data from the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA; it was made possible by the generous financial support of the W. M. Keck Foundation. This work made use of the NASA/ IPAC Extragalactic Database, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. R.C.T. is a Luis W. Alvarez Fellow at the Lawrence Berkeley National Laboratory. R.J.F is a Clay Fellow at the Harvard-Smithsonian Center for Astrophysics.",
year = "2009",
month = dec,
day = "3",
doi = "10.1038/nature08579",
language = "אנגלית",
volume = "462",
pages = "624--627",
journal = "Nature",
issn = "0028-0836",
publisher = "Nature Research",
number = "7273",
}