Computational Astrophysics
In the field of computational astrophysics, I am most
interested in the classical N-body gravitational
problem, with an emphasis on collisional physics.
Applications range from planet formation to granular dynamics.
I mostly use the computer
code pkdgrav
for my simulations, which one day soon we hope to make
public!
Planetary Science
I started my career in astronomy being involved with the
search for extrasolar planets, but gradually turned to planet
formation and other planetary science fields where I could
apply my interest in computational astrophysics. My present
focus is on the dynamics and evolution of small solar system
bodies, especially asteroids.
Pkdgrav
Pkdgrav is a parallel
N-body tree code originally designed for cosmology
simulations at
the N-body
Shop, part of
the Department of
Astronomy at
the University of
Washington. I added collisional physics to the code so it
could be applied to problems in planetary science. This
includes adding a large set of initial condition, analysis,
and visualization tools. The most recent development,
starting with my former graduate student Steve Schwartz's
graduate work, was to add a soft-sphere discrete element
method to the code for more realistic treatment of particle
contact physics suitable for high-resolution granular dynamics
simulations. Until a public release is available, interested
potential collaborators are welcome
to contact me.
Missions
Recently I've been lucky enough to get involved in some
exciting space missions! I was Co-Investigator and
Lead of the Dynamics Working Group for
the DART
mission to test kinetic impactor technology on the satellite
of the Didymos binary asteroid system. I was also a
Collaborator on the OSIRIS-REx
sample-return mission to asteroid Bennu and
the New
Horizons mission to Pluto and beyond. I am an
international participant on ESA's Hera mission to return to Didymos.
My Papers
You can browse my
publications here. My full CV with a
comprehensive list of publications is
here
(PDF).
The following are probably my most influential papers so far as lead or co-author, in time order:
- Lin, D.N.C.,
Bodenheimer, P., Richardson, D.C. 1996. Orbital migration of
the planetary companion of 51 Pegasi to its present
location. Nature 380, 606-607—Appearing shortly
after the discovery of the first extrasolar planet orbiting
a normal star, this paper continues to be cited for our
proposed explanations for why the planet is so close to its
host star.
- Richardson,
D.C., Bottke Jr., W.F., Love, S.G. 1998. Tidal distortion
and disruption of Earth-crossing asteroids. Icarus 134,
47-76—This paper laid much of the groundwork for
the idea that asteroids are fragile gravitational aggregates
that can be disrupted by relatively weak forces.
- Richardson,
D.C., Quinn, T., Stadel, J., Lake, G. 2000. Direct
large-scale
N-body simulations of planetesimal dynamics. Icarus
143, 45-59—The paper that first introduced pkdgrav as a tool for studying
planetesimal dynamics.
- Michel, P., Benz,
W., Tanga, P., Richardson, D.C. 2001. Collisions and
gravitational reaccumulation: Forming asteroid families and
satellites. Science 294, 1696-1700—The first in a
series of papers (including one in Nature) that demonstrates
asteroids form families by gravitational reaccumulation of
debris following catastrophic impacts.
- Leinhardt, Z.M.,
Richardson, D.C. 2005. Planetesimals to
protoplanets. I. Effect of fragmentation on terrestrial
planet formation. Astrophys. J. 625, 427-440—The
first implementation of a self-consistent model of
planetesimal fragmentation in a planet-formation code, based
on earlier simulations of collisions between planetesimals
represented as gravitational aggregates [see here], and followed later
by studies of the effect of dynamical friction from the
debris.
- Walsh, K.J.,
Richardson, D.C., Michel, P. 2008. Rotational breakup as the
origin of small binary asteroids. Nature 454,
188-191—This explanation for the formation of
small binary asteroids generated a lot of media attention.
It was also ranked as one of the top 10 astronomy stories of
2008 by Astronomy magazine!
Former Ph.D. Students
(For Alice and Carrie, I was Academic Advisor.)
- Dr.
Zoë M. Leinhardt, "Planetesimal Evolution
and the Formation of Terrestrial Planets" (2005)
- Dr. Kevin
J. Walsh, "Forming Binary Near-Earth Asteroids
from Tidal Disruptions" (2006)
- Dr. Randall
P. Perrine, "N-body Simulations with Cohesion
in Dense Planetary Rings" (2011)
- Dr. Stephen
R. Schwartz, "The Development and Implementation of
Numerical Tools for Investigation into the Granular
Dynamics of Solid Solar System Bodies" (2013)
- Dr. Ronald-Louis
G. Ballouz, "Numerical Simulations of Granular
Physics in the Solar System" (2017)
- Dr. Alice
R. Olmstead, "An Assessment of Professional
Development for Astronomy and Physics Faculty:
Expanding Our Vision of How to Support Faculty’s
Learning About Teaching" (2016)
- Dr. Harrison
Agrusa, "On the Dynamics of
Binary Asteroids Applied to DART
Mission Target (65803) Didymos"
(2022)
- Dr. Carrie
Holt, "A Song of Fire & Ice:
Evolutionary Properties of Hot & Cold
Small Bodies" (2023)
- Dr. Julian
Marohnic, "Mechanical Evolution
of Small Solar System Bodies" (2023)
