The ORION Astrophysical Adaptive Mesh Refinement Code

From Uranometria (1603) by Johann Bayer. Engraving by Alexander Mair.

The Code

With my long-standing colleagues Richard Klein (LLNL/UCB), Christopher McKee (UCB), Phillip Colella (UCB), Mark Krumholz (Princeton), Jeffrey Greenough (LLNL), and Louis Howell (LLNL) and others, we have developed ORION -- one of the most advanced codes for direct numerical simulations of star formation. ORION includes multispecies higher-order Godunov hydrodynamics, self-gravity, flux-limited radiation diffusion (both grey and multifrequency), nonlinear thermal conduction, ideal higher-order Godunov MHD, Lagrangian sink cell particles, stellar evolution models, and stellar outflows -- all included in a single unified, fully-adaptive, and fully-parallel framework.

ORION has a long and distinguished ancestry, dating back to the original block-structured adaptive mesh refinement code developed by Berger and Colella in the late 1980s. Its direct ancestors are the HyperCLaw AMR code of Bell and colleagues and the RAPTOR code of Greenough and Howell.

The Science

ORION has been and is being applied to a wide variety of demanding problems of key interest in the study of the interstellar medium and star formation.

We have applied ORION to low-mass single and multiple star formation within isolated turbulent cores, and (with Fumitaka Nakamura of Niigata University) to shocked clouds. We are currently applying it to cluster formation in turbulent GMC clumps both with and without stellar feedback, and (with PS Li) to core formation in turbulent magnetized GMCs.

In addition, my collaborators have used ORION to study Bondi-Hoyle accretion in a turbulent medium, and to high-mass star formation.

The Gallery

Single and Multiple Star Formation in Turbulent Molecular Cloud Cores


Shock-Cloud Interactions

0 Nakamura et al, 2006

Turbulent Fragmentation


Magnetized Gravitational Collapse


Stellar Outflows