Consequences of ancient near-Earth supernovae on the heliosphere and throughout the solar system

Miller, Jesse Alan

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https://hdl.handle.net/2142/117814 Copy

Description

Title

Consequences of ancient near-Earth supernovae on the heliosphere and throughout the solar system

Author(s)

Miller, Jesse Alan

Issue Date

2022-12-02

Director of Research (if dissertation) or Advisor (if thesis)

Fields, Brian D

Doctoral Committee Chair(s)

Fields, Brian D

Committee Member(s)

• Ricker, Paul M
• Looney, Leslie W
• Shen, Yue

Department of Study

Astronomy

Discipline

Astronomy

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• supernovae
• near-Earth supernovae
• cosmic rays
• mass extinctions
• heliosphere

Abstract

An abundance of data now shows evidence for recent supernova activity within 100 pc of our solar system in the last 10 Myr. Two supernovae, one 3 Myr ago and the other 7 Myr ago, have been identified by careful measurements of 60Fe in the geological record. This dissertation explores some effects nearby supernovae have had throughout the solar system. First, we examine how cosmic rays impinging on the surface of asteroids introduces a background 60Fe flux. This background is found to be approximately two orders of magnitude smaller than the amount delivered by the supernova. Next, we propose that a mass extinction in the late Devonian 360 Myr ago was triggered by a nearby supernova 20 pc away. Current evidence is consistent with this idea, and we show how measurements of long-lived radioisotopes can test this hypothesis. After that, we run a suite of simulations showing how the onset of the supernova blast impacts and compresses the heliosphere. Using 2D axisymmetry and idealized hydrodynamics, we show that ram pressure balance gives the penetration distance into the solar system. The Earth is protected from the blast by the solar wind, but much of the outer solar system is left exposed. As a result, the \fe60 observed on Earth must have arrived in the form of dust. The heliosphere rebounds over the following 300 kyr as the supernova remnant continues to evolve and fade. Based on the recent detection of 244Pu, we then suggest that the local interstellar medium was enriched by a kilonova explosion. The supernova, then, was unlikely to have made 244Pu, but instead pushed the pre-existing isotope onto Earth. Given that the r-process occurred, the isotope 129I should be have a particularly high abundance. Lastly, we present a model for how the supernova blast dynamically pushes bodies in the Oort cloud. Small particles like dust grains are completely ejected, but objects larger than 10 m are unaffected. While this dissertation explores many aspects of how supernovae interact with Earth and the solar system, the scope is necessarily incomplete. This field is ripe for further activity from a variety of scientists, including astronomers, nuclear physicists, geologists, biologists, planetary scientists, and more.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Jesse Miller

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