Detecting Supernovae in Tree Ring Radiocarbon Records

Project summary

The goal of this project was to use measurements of radioactive carbon (C-14) in tree rings to detect both known supernovae and verify supernova candidates identified from ancient Chinese literature, in particular the supposed SN 185. The high-energy radiation from the explosion of a nearby star would cause an overproduction of radiocarbon in the upper atmosphere, which would work its way into plant matter produced that year and therefore present an anomaly in its radiocarbon dating. This project was sparked by our interest in the results of Miyake et al. (2012) and their subsequent work, detecting a massive spike in radiocarbon production in 774 AD and candidates in other years, which could be ascribed to a nearby supernova or to a ‘superflare’ from the Sun.

The initial results of the BII-funded radiocarbon dating did not detect any evidence of a supernova or anomalous solar activity. Nevertheless, this is not to be construed as a failure, as it was a very small sample of years and we are looking for intrinsically rare events. With the Fell Fund contribution, we are hopeful that we will detect more of these events.

The results of this project were communicated in a presentation at the International Radiocarbon Conference 2015, in Dakar, Senegal. In particular, we strongly constrained the amplitude of radiocarbon signals from known supernovae, including SN 1604 (Tycho), SN1572 (Kepler), SN 185 (China) and a putative Star of Bethlehem. That we only detect SN 1054 (Crab), the brightest in recorded history, is significant in interpreting the large Miyake events, lending credence to the hypothesis that these are in fact the results of massive solar flares.

Moving forwards, one goal of this project is moving to understanding whether these events are solar superflares, and understanding when and why these happen. We know from the NASA that man G2-type stars like the Sun display superflares, and understanding why the Sun is comparatively quiet is a significant problem in stellar activity theory. Identifying candidate superflares in the distant past will help us understand the solar activity cycle in the present day.

The main goal, however, is to use these single-year anomalies to provide high-precision dates for archaeological artefacts. At present, we only have exact, annual dates for events as far back as ancient Greece. Large sections of the chronology of, in particular, the Late Bronze Age in the Near East are not anchored to an accurate absolute chronology, but have very well known relative chronologies, for example from the known dynasties of Egyptian rulers. If we can identify a spike in the Late Bronze Age and tie it to an artefact naming, say, the year in an Egyptian calendar, we will push back our annals of dated, recorded history a thousand years and establish a single chronology for our civilization.

Lead investigator

Benjamin Pope, Department of Physics and Balliol College, University of Oxford

Research team

Dr Michael Dee, Research Laboratory for Archaeology and the History of Art, University of Oxford

Professor Sturt Manning, Goldwin Smith Professor of Classical Archaeology, Cornell University

Contact details for enquiries

Please email the lead investigator, Ben Pope, for any queries regarding this project.