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Ethan A. N. Deneault

  Deneault_E 

Ethan A. N. Deneault

Assistant Professor of Physics
  • Worcester Polytechnic Institute, Physics and Humanities, B.S.
  • Clemson University, Physics, M.S.
  • Clemson University, Physics, Ph.D.
 

Research Interests

Primitive meteorites are ancient stones left over from the formation of the solar system that have been trapped by Earth's gravity and crashed onto its surface. A particular subclass of these primitive meteorites, known as carbonaceous chondrites, show no evidence of ever having been heat-processed in the early solar system. This lends the carbonaceous chondrites a particular composition that reflects the materials present at the formation of the solar system 4.5 billion years ago.
 

Deneault Research 1
©1999 Dr. Larry Nittler
 

Within the interior of these chondrites can be found a peculiar type of small dust grain, which can be extracted from the meteoritic matrix and studied. The composition of these tiny (only a few microns in size) grains is remarkable. Although some grains exhibit a similar isotopic composition to that of the Earth or Sun, a vast majority of them do not, indicating that they were not formed with the solar system.

Where do they come from? Careful study of their composition reveals that these grains are, in fact, the remnants of ancient stars that lived and died long before the Sun was born. In a sense, these presolar grains are a type of "stellar fossil', created in the cooling gases ejected by dying stars and fortuitously swept up in the nebula that created our own solar system. The study of these grains leads directly toward our understanding about how the chemical elements evolved in our galaxy.

I am interested in the development of models that will accurately describe the condensation of presolar grains within the ejecta of supernovae. A supernova is a profoundly violent event – the explosive death of a massive star. Within the radioactive outflows from the detonation, inorganic carbon chemistry drives the condensation process, creating both graphite as well as silicon carbide. Understanding the processes by which these condensates form is an important step in our understanding of the supernovae both observationally and theoretically.
 

Deneault Research 2
This graph represents the fraction of the total atoms in the ejecta that are bound in CO molecules as a function of temperature and the rate of radioactive disruption of CO.
 

Current Projects

 Deneault Research 3
This graph describes the number of atoms per grain species for carbon grains from C10 (far left) to C1015 (far right). The number of grains created depends strongly on the density of the ambient medium as well as the rate at which CO is disrupted.
 

References

Deneault, E.A.-N., Clayton, D.D., & Meyer, B.S. Growth of Carbon Grains in Supernova Ejecta 2006, ApJ, 638, 234

Deneault, E.A.-N., Clayton, D.D., & Heger, A. Supernova Reverse Shocks: SiC Growth and Isotopic Composition 2003, ApJ, 594, 312

Clayton, D.D., Deneault, E.A.-N., & Meyer, B.S. Condensation of Carbon in Radioactive Supernova Gas 2001, ApJ, 562, 480

  1. Development of a paradigm for the condensation of silicon carbide in a low-density radioactive gas.
  2. A model for the condensation of SiC and C(s) in supernova ejecta, parameterized by the ratios of Si/C and C/O, the radioactivity flux and the density. The results of this investigation will then be compiled into a database.
  3. The (Mis-)adventures of Bob and Jane. I've been writing this book on and off for the past couple of years. It's designed to be a supplementary textbook/study guide for Introductory Algebra and Calculus based Physics courses.