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.
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.
©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
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.
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.
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.
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
- Development of a paradigm for the condensation of silicon carbide in a low-density radioactive gas.
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.
- 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.