Speaker
Description
Rapid spikes observed in the tree-ring $^{14}$C record are caused by extreme solar proton storms or high-energetic particles events. Six of these “Miyake” events have been confirmed with 10Be in ice cores at 774 CE, 993 CE, 664 BCE, 5259 BCE, 7176 BCE, and 12450 BCE. There are also a number of $^{14}$C excursions attributed to solar effects that are not yet confirmed by other cosmogenic nuclides. There are other smaller-magnitude spikes in the $^{14}$C record in tree rings were detected but their origin is not explained or associated with known cosmic events. It has been previously noted that a rapid increase in production rate of cosmogenic isotopes could also be related to a supernova explosion (SN) or gamma-ray bursts (GRB). Modeling of the effect of energetic photons from an SN on the Earth's atmosphere suggested the possibility to measure it through production of cosmogenic isotopes (Menjo et al. 2005; Pavlov et al. 2013). These ideas have already been explored by several different studies (Damon et al. 1995; Menjo et al. 2005; Dee et al. 2023). We studied $^{14}$C content of tree rings from five locations during the historic supernova explosion SN1181 documented by Chinese and Japanese astronomers as a "guest star" in the Cassiopeia constellation to investigate its possible impact on the $^{14}$C variance in the atmosphere and the cosmogenic isotope production rate. Three new annually resolved AMS radiocarbon series were developed for the 1170-1190 CE interval from hemlock collected in Alaska, white spruce from the Columbia Icefields of Alberta, and larch from Indigirka River in eastern Siberia. We found no clear signature in the radiocarbon content of tree rings to response to the historic supernova explosion. We also compared our results to two previous records over the same time frame, from sequoia in California and a European oak chronology (Eastoe et al. 2019, Brehm et al. 2021). The ∆$^{14}$C signal did not show any significant and consistent increase around 1181 CE. Also, modeling of the $^{14}$C production rate calculated with a carbon-cycle 22-box model revealed no significant increase around 1181 CE. The inconsistent signature of the SN1181 event observed for $^{14}$C in tree rings gives a similar response as the radiocarbon pattern previously observed for the SN1054 Crab Nebula supernova event in several studies.
Co-author list:
Irina P. Panyushkina (3), Mihály Molnár (2), Támas Varga (2,4), Valerie Livina (5), Gregory Wiles (6), Nicholas Wiesenberg (6), Robert J. S. Wilson (7)
(2) Isotope Climatology and Environmental Research Centre, Institute for Nuclear Research, Debrecen, Hungary
(3) Laboratory of Tree‑Ring Research, University of Arizona, Tucson, AZ, USA
(4) Max‑Planck‑Institut für Biogeochemie, Jena, Germany
(5) National Physical Laboratory, Teddington, Middlesex, UK
(6) College of Wooster, Wooster, Ohio, USA
(7) University of St Andrews, UK