Abstract
Samples of two deep-sea sediment cores from the Indian Ocean are analyzed with accelerator mass spectrometry (AMS) to search for traces of recent supernova activity around 2 Myr ago. Here, long-lived radionuclides, which are synthesized in massive stars and ejected in supernova explosions, namely 26Al, 53Mn and 60Fe, are extracted from the sediment samples. The cosmogenic isotope 10Be, which is mainly produced in the Earths atmosphere, is analyzed for dating purposes of the marine sediment cores. The first AMS measurement results for 10Be and 26Al are presented, which represent for the first time a detailed study in the time period of 1.7-3.1 Myr with high time resolution. Our first results do not support a significant extraterrestrial signal of 26Al above terrestrial background. However, there is evidence that, like 10Be, 26Al might be a valuable isotope for dating of deep-sea sediment cores for the past few million years.
Highlights
The findings of an enhancement of SN-ejected radionuclides in a deep-sea sediment would corroborate the theory of a recent SN close to the solar vicinity
The first accelerator mass spectrometry (AMS) measurement results for 10Be and 26Al are presented, which represent for the first time a detailed study in the time period of 1.7-3.1 Myr with high time resolution
We studied samples of 3 kyr integration time for every 20-30 kyr
Summary
The findings of an enhancement of SN-ejected radionuclides in a deep-sea sediment would corroborate the theory of a recent SN close to the solar vicinity. The 60Fe signal identified by [5] is a valuable hint to such events in the local interstellar medium, and the existence of the Local Bubble, in which our solar system is embedded [10]. This interstellar cavity has been produced by ∼20 SN explosions starting around 14 Myr ago in a stellar moving group of stars belonging today to the the Sco-Cen association. That enough 60Fe material can be transported from these SN origin to Earth, to produce such a signal as observed in the ferromanganese crust [11]
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