Astrophysics researchers at UC San Diego have advanced their understanding of star formation with the help of some major computational resources from San Diego Supercomputer Center (SDSC) at the UC San Diego and the National Institute for Computational Science (NICS) at Oak Ridge National Laboratory.
The three researchers describe the results of their study that yielded the results in a newly published paper, called “A Supersonic Turbulence Origin of Larson’s Laws.” The trio report on the origin of three observed correlations between various properties of molecular clouds in the Milky Way galaxy known as Larson’s Laws.
Larson’s Laws were named by professors teaching the three principles based on a seminal 1981 paper by Richard Larson, an Emeritus Professor of Astronomy at Yale. That paper describes the observation-based relationships of the structure and supersonic internal motions of molecular clouds where stars form.
Their analysis was based on data from a suite of six ISM (interstellar medium) simulations, which include the effects of self-gravity, turbulence, magnetic fields and multiphase thermodynamics. Both the simulations and analysis were performed on the DataStar supercomputer (now-decommissioned), and the Trestles and Triton systems at the San Diego Supercomputer Center, as well as on the Kraken and Nautilus systems at the National Institute for Computational Science.
A writeup on this study penned by Jan Zverina at UCSD, notes that the “supercomputer simulations support a turbulent interpretation of Larson’s relations.”
“The study concludes that there are not three independent Larson laws, but that all three correlations are due to the same underlying physics, i.e. the properties of supersonic turbulence,” reports Zverina.
Larson gave the following statement in response to the new research: “After decades of inconclusive debate about the interpretation of the correlations among molecular cloud properties that I published in 1981, it’s gratifying to see that my original idea that they reflect a hierarchy of supersonic turbulent motions is well supported by these detailed new simulations showing that the debated complicating effects of gravity, magnetic fields, and multiphase structure do not fundamentally alter the basic picture of a turbulent cascade.”
The research team includes lead author Alexei Kritsuk, a research physicist with UC San Diego’s Physics Department and Center for Astrophysics & Space Sciences (CASS), Michael Norman, Director of the San Diego Supercomputer Center and a Distinguished Professor of physics at UC San Diego, and Christoph T. Lee, an undergraduate researcher with CASS.
Larson’s original paper and this follow-up work both appear in the same prominent astronomy and astrophysics journal: Great Britain’s Monthly Notices of the Royal Astronomical Society.