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# Observation of 23 Supernovae That Exploded

Firestone, R. B.

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{
"description": "Four supernovae (SNe), exploding 300 pc from Earth, were recorded 44, 37, 32, and 22 kyr ago in the radiocarbon (14C) record during the past 50 kyr. Each SN left a nearly identical signature in the record, beginning with an initial sudden increase in atmospheric radiocarbon, when the SN exploded, followed by a hiatus of 1500 yr, andconcluding with a sustained 2000 yr increase in global radiocarbon due to \u03b3 -rays produced by diffusive shock in the SN remnant (SNR). For the past 18 kyr excess radiocarbon has decayed with the 14C half-life. SN22kyrBP,\nis identified as the Vela SN that exploded 250 \u00b1 30 pc from Earth. These SN are confirmed in the 10Be, 26Al, 36Cl, and NO\u22123 geologic records. The rate of near-Earth SNe is consistent with the observed rate of historical SNe giving a galactic rate of 14 \u00b1 3 kyr\u22121 assuming the Chandra Galactic Catalog SNR distribution. The Earth has been used as a calorimeter to determine that \u22482 \u00d7 1049 erg were released as \u03b3 -rays at the time of each SN explosion and \u22481050 erg in \u03b3 -rays following each SN. The background rate of 14C production by cosmic rays has been\ndetermined as 1.61 atoms cm\u22122 s\u22121. Approximately 1/3 of the cosmic ray energy produced by diffusive shock in the SNR was observed to be emitted as high-energy \u03b3 -rays. Analysis of the 10Be/9Be ratio in marine sediment identified 19 additional near-Earth SNe that exploded 50\u2013300 kyr ago. Comparison of the radiocarbon record with global temperature variations indicated that each SN explosion is correlated with a concurrent global warming of \u22483\u25e6C\u20134\u25e6C..",
"creator": [
{
"@type": "Person",
"name": "Firestone, R. B."
}
],
"headline": "Observation of 23 Supernovae That Exploded",
"datePublished": "2014-06-11",
"url": "https://zenodo.org/record/895414",
"@context": "https://schema.org/",
"identifier": "https://doi.org/10.1088/0004-637x/789/1/29",
"@id": "https://doi.org/10.1088/0004-637x/789/1/29",
"@type": "ScholarlyArticle",
"name": "Observation of 23 Supernovae That Exploded"
}
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