Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

We will search for supernova-produced radionuclides in deep-sea sediment cores originating from the Indian Ocean. We aim to measure the long-lived radionuclides ²⁶Al (t_1/2 = 0.7 Myr), ⁶⁰Fe (t_1/2 = 2.6 Myr), ⁵³Mn (t_1/2 = 3.7 Myr) and ²⁴⁴Pu (t_1/2= 80 Myr) at different laboratories in sediment samples with high time resolution.
A positive signal will also confirm a previous finding of an enhanced 60Fe content in a ferromanganese crust [1]. The above mentioned radionuclides are commonly synthesized in massive stars and ejected by supernova (SN) explosions. If such a SN event happens in the solar vicinity, the expanding SN envelope might hit the solar system and leave certain traces in terrestrial archives. An indication to recent SN activity is the existence of a cavity consisting of thin, hot gas in the local interstellar medium, embedding our solar system. This superbubble, called the Local Bubble, was presumably produced by 14-20 SN explosions starting 14 Myr ago [2].
Because SNe and their ejecta are a site for dust formation, there might be a chance of finding such radionuclides in dust particles deposited in such terrestrial archives, like deep-sea sediments. The measurements will be carried out with accelerator mass spectrometry (AMS) utilizing laboratories with the highest sensitivities for these long-lived radionuclides.
[1] K. Knie, et al., Physical Review Letters 93, 17 (2004).
[2] B. Fuchs et al., Monthly Notices of the Royal Astronomical Society 373, 993-1003 (2006).