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Title:Supernova shrapnel: nearby supernovae and dust transport in the ISM
Author(s):Fry, Brian Joseph
Director of Research:Fields, Brian D
Doctoral Committee Chair(s):Fields, Brian D
Doctoral Committee Member(s):Ricker, Paul M; Looney, Leslie W; Thaler, Jon J
Department / Program:Astronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
radioactive isotopes
Abstract:The last 2 decades have seen the proposal, detection, and confirmation of live ^60Fe radioisotopes from an extra-solar source on Earth, showing an event outside the Solar System directly delivered material to the Earth since its formation. This work examines the possible sources for the ^60Fe and models the passage of the material from its source through the Solar System to the ocean floor. We consider the production and deposition on Earth of isotopes with half-lives in the range 10^5 to 10^8 years that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGBs) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the ^60Fe and ^26Al signatures, and extend these estimates to include ^244Pu and ^53Mn. We show that (i) the ^60Fe yield rules out the TNSN and KN interpretations, (ii) the ^60Fe signals highly constrain a SAGB interpretation but do not completely them rule out, (iii) are consistent with a CCSN origin, and (iv) are highly compatible with an ECSN interpretation. We also examine various influences on the path of interstellar dust carrying ^60Fe from a SN through the Heliosphere, with the aim of estimating the final global distribution on the ocean floor. We study the influences of magnetic fields, angle of arrival, wind and ocean cycling of SN material on the concentrations at different locations. We find that the passage of SN material through the mesosphere/lower thermosphere (MLT) is the greatest influence on the final global distribution, with ocean cycling causing lesser alteration as the SN material sinks to the ocean floor. SN distance estimates in previous works that assumed a uniform distribution are a good approximation. Including the effects on surface distributions, we estimate a distance of 46^(+10)_(-6) pc for an ECSN progenitor. We note that the SN dust retains directional information to within 1^(circ) through its arrival in the inner Solar System, so that SN debris deposition on inert bodies such as the Moon will be anisotropic, and thus could in principle be used to infer directional information. Lastly, we examine the various influences on the path of dust within a SN remnant (SNR) to determine when/if the dust decouples from the plasma, how much it is sputtered, and where within the ejecta the dust is located. We find that the inclusion of Rayleigh-Taylor (R-T) instabilities are important in studying dust survival as R-T instabilities influence the location of the SN's reverse shock. We also find the presence of a magnetic field within the shocked ISM material will limit the passage of SN dust grains reflecting them or trapping within the heart of the SNR.
Issue Date:2016-07-08
Rights Information:Copyright 2016 Brian J. Fry
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08

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