Analyzing the composition of an Antarctic ice core, Japanese researchers say they have found the chemical fingerprints of two well-known supernovas from the 11th century, as well as evidence of an 11-year solar cycle from the same century.
“This is one of the first times that a distinct 11-year solar cycle has been observed for a period before the landmark studies of sunspots by Galileo Galilei with his telescope,” Yuko Motizuki of the RIKEN Nishina Center for Accelerator-Based Science in Wako, Japan, and his colleagues assert in an article posted online February 20 (http://arxiv.org/abs/0902.3446). The findings, the team adds, “have significant consequences” for dating ice cores, discovering previously unknown supernovas in the Milky Way and revealing the history of the solar cycle.
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