Numerical studies on the link between radioisotopic signatures on earth and the formation of the local bubble: I. 60Fe transport to the solar system by turbulent mixing of ejecta from nearby supernovae into a locally homogeneous interstellar medium
<i>Context. <i/>The discovery of radionuclides like <sup>60<sup/>Fe with half-lives of million years in deep-sea crusts and sediments offers the unique possibility to date and locate nearby supernovae.<i>Aims. <i/>We want to quantitatively establish that the <s...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
11 August 2017
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| In: |
Astronomy and astrophysics
Year: 2017, Volume: 604, Pages: A81 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201629837 |
| Online Access: | Verlag, kostenfrei, Volltext: http://dx.doi.org/10.1051/0004-6361/201629837
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| Author Notes: | M.M. Schulreich, D. Breitschwerdt, J. Feige, and C. Dettbarn |
| Summary: | <i>Context. <i/>The discovery of radionuclides like <sup>60<sup/>Fe with half-lives of million years in deep-sea crusts and sediments offers the unique possibility to date and locate nearby supernovae.<i>Aims. <i/>We want to quantitatively establish that the <sup>60<sup/>Fe enhancement is the result of several supernovae which are also responsible for the formation of the Local Bubble, our Galactic habitat.<i>Methods. <i/>We performed three-dimensional hydrodynamic adaptive mesh refinement simulations (with resolutions down to subparsec scale) of the Local Bubble and the neighbouring Loop I superbubble in different homogeneous, self-gravitating environments. For setting up the Local and Loop I superbubble, we took into account the time sequence and locations of the generating core-collapse supernova explosions, which were derived from the mass spectrum of the perished members of certain stellar moving groups. The release of <sup>60<sup/>Fe and its subsequent turbulent mixing process inside the superbubble cavities was followed via passive scalars, where the yields of the decaying radioisotope were adjusted according to recent stellar evolution calculations.<i>Results. <i/>The models are able to reproduce both the timing and the intensity of the <sup>60<sup/>Fe excess observed with rather high precision, provided that the external density does not exceed 0.3 cm<sup>-3<sup/> on average. Thus the two best-fit models presented here were obtained with background media mimicking the classical warm ionised and warm neutral medium. We also found that <sup>60<sup/>Fe (which is condensed onto dust grains) can be delivered to Earth via two physical mechanisms: either through individual fast-paced supernova blast waves, which cross the Earth’s orbit sometimes even twice as a result of reflection from the Local Bubble’s outer shell, or, alternatively, through the supershell of the Local Bubble itself, injecting the <sup>60<sup/>Fe content of all previous supernovae at once, but over a longer time range. |
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| Item Description: | Die 60 im Titel ist hochgestellt Gesehen am 18.10.2017 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201629837 |