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Discovery of a supernova explosion at half the age of the Universe

An Erratum to this article was published on 19 March 1998


The ultimate fate of the Universe, infinite expansion or a big crunch, can be determined by using the redshifts and distances of very distant supernovae to monitor changes in the expansion rate. We can now find1 large numbers of these distant supernovae, and measure their redshifts and apparent brightnesses; moreover, recent studies of nearby type Ia supernovae have shown how to determine their intrinsic luminosities2,3,4—and therefore with their apparent brightnesses obtain their distances. The >50 distant supernovae discovered so far provide a record of changes in the expansion rate over the past several billion years5,6,7. However, it is necessary to extend this expansion history still farther away (hence further back in time) in order to begin to distinguish the causes of the expansion-rate changes—such as the slowing caused by the gravitational attraction of the Universe's mass density, and the possibly counteracting effect of the cosmological constant8. Here we report the most distant spectroscopically confirmed supernova. Spectra and photometry from the largest telescopes on the ground and in space show that this ancient supernova is strikingly similar to nearby, recent type Ia supernovae. When combined with previous measurements of nearer supernovae2,5, these new measurements suggest that we may live in a low-mass-density universe.

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Figure 1: Spectrum of SN1997ap placed within a time sequence of five ‘normal’ type Ia supernovae.
Figure 2: Photometry points for SN1997ap.
Figure 3: SN1997ap at z = 083
Figure 4: Contour plot of the best fit confidence regions in the ΩΛ versus ΩM plane for.

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The authors are members of the Supernova Cosmology Project. We thank CTIO, Keck, HST, WIYN, ESO and the ORM–La Palma observatories for a generous allocation of time, and the support of dedicated staff in pursuit of this project; D. Harmer, P. Smith and D. Willmarth for their help as WIYN queue observers; and G. Bernstein and A. Tyson for developing and supporting the Big Throughput Camera which was instrumental in the discovery of this supernova.

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Correspondence to S. Perlmutter.

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Physics Department, Stockholm University, Box 6730, S-11385 Stockholm, Sweden

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Perlmutter, S., Aldering, G., Valle, M. et al. Discovery of a supernova explosion at half the age of the Universe. Nature 391, 51–54 (1998).

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