2010 Annual Science Report
Arizona State University Reporting | SEP 2009 – AUG 2010
Astrophysical Controls on the Elements of Life, Task 4: Model the Injection of Supernova Material Into Protoplanetary Disks
The goal of this task is to determine how much supernova material can make its way into a forming solar system, after the star has formed and is surrounded by a protoplanetary disk. This supernova material may contain radioactive isotopes like 26Al, which is the primary mechanism by which asteroids melted and which may control delivery of water and other elements to terrestrial planets. This supernova material may also change the abundance ratios of bioessential elements.
We have made progress toward understanding how supernova ejecta is injected into disks, on two main fronts: (a) direct modeling of the process, and (b) using isotopic evidence from meteorites to constrain how this happened in our disk (if at all).
On the first front, we published a paper in March 2010, the second paper from the thesis of ASU Graduate Student Nic Ouellette (advisor: Desch), showing how dust grains condensed in supernova ejecta can be injected into a disk [Ouellette, Desch & Hester 2010, ApJ 711, 597]. In that paper we also discuss the evidence for clumpy supernova ejecta, which is an important component of all work in Tasks 3 and 4. We also consider the evidence for efficient condensation of dust in supernovae, which is a poorly constrained and controversial input.
We have tried to constrain this input in a research effort along the second front. Postdoc Themis Athanassiadou and Desch have been investigating ways to constrain the degree to which 60Fe condenses into large (micron-sized) grains using models of how the earth acquired live 60Fe 3 Myr ago, then applying those constraints to the study of injection into the protoplanetary disk. This work was presented by Athanassiadou at AbSciCon 2010 and again at the Meteoritical Society meeting in New York in July, 2010. Also along the second front, graduate student Carola Ellinger (advisor: Patrick Young), with the assistance of Desch, have worked on the question of whether injection of 26Al into the disk necessarily would yield significant shifts in oxygen isotopes in the solar nebula. Carola Ellinger gave an oral presentation on this work at AbSciCon 2010, and this work was recently accepted for publication in the Astrophysical Journal. Finally, mixing of radionuclides in the protoplanetary disk was specifically examined by Ouellette et al.(2009), published in Geochimica et Cosmochmica Acta.
PROJECT INVESTIGATORS:Steven Desch
PROJECT MEMBERS:Francis Timmes
RELATED OBJECTIVES:Objective 1.1
Formation and evolution of habitable planets.
Sources of prebiotic materials and catalysts