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Supernovae and Single-Year Anomalies in the Atmospheric Radiocarbon Record

Published online by Cambridge University Press:  01 August 2016

Michael Dee*
Affiliation:
University of Oxford – RLAHA, South Parks Road, Oxford OX1 3QY, United Kingdom
Benjamin Pope
Affiliation:
University of Oxford – Physics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, United Kingdom
Daniel Miles
Affiliation:
University of Oxford – RLAHA, South Parks Road, Oxford OX1 3QY, United Kingdom
Sturt Manning
Affiliation:
Cornell University – Cornell Tree-Ring Laboratory, Ithaca, New York, USA
Fusa Miyake
Affiliation:
Nagoya University – ISEE, Nagoya, Japan
*
*Corresponding author. Email: michael.dee@rlaha.ox.ac.uk.
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Abstract

Single-year spikes in radiocarbon production are caused by intense bursts of radiation from space. Supernovae emit both high-energy particle and electromagnetic radiation, but it is the latter that is most likely to strike the atmosphere all at once and cause a surge in 14C production. In the 1990s, it was claimed that the supernova in 1006 CE produced exactly this effect. With the 14C spikes in the years 775 and 994 CE now attributed to extreme solar events, attention has returned to the question of whether historical supernovae are indeed detectable using annual 14C measurements. Here, we combine new and existing measurements over six documented and putative supernovae, and conclude that no such astrophysical event has yet left a distinct imprint on the past atmospheric 14C record.

Information

Type
Rapid Event in the Natural Atmospheric 14C Content
Copyright
© 2016 by the Arizona Board of Regents on behalf of the University of Arizona 
Figure 0

Table 1 Historical records of ephemeral stars thought to be galactic supernovae. The observational records come from Tse-Tsung (1957) and Green and Stephenson (2003); the distances from Earth for SN185 and SN393 come from Damon et al. (1995) and the remainder from Firestone (2014), but estimates vary widely.

Figure 1

Figure 1 Published Δ14C data on the Miyake event in 775 CE. The four Northern Hemisphere data sets [Japan (Miyake et al. 2012); Germany (Usoskin et al. 2013); USA and Russia (Jull et al. 2014) pertain to the left-hand axis, and the New Zealand data (Güttler et al. 2015) to the right-hand axis]. The latter is offset by 5‰ to account for the differences in absolute activity in the two hemispheres. Please see online version to view figure in color.

Figure 2

Figure 2 New and previously published Δ14C data over historical observations of known or potential near-Earth supernovae. The horizontal axis is divided into the 5 calendar years leading up to the observation and the 10 years after it.

Figure 3

Table 2 The six astronomical records investigated in this study. Where available, data are given for the 5 years leading up to the first observation and the 10 years thereafter. Weighted averages were calculated for SN1006, as multiple data sets were available for this event. The supplementary online material gives details of all the underlying data (Table S1), as well as the new results expressed as conventional 14C ages (Table S2).

Supplementary material: PDF

Dee supplementary material

Figure S1 and Tables S1-S2

Download Dee supplementary material(PDF)
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