Astrophysicists at the University of California, Berkeley, and Lawrence Livermore National Laboratory (LLNL) have exploded one of two competing theories about how stars form inside immense clouds of interstellar gas.
A slice through a 3-D simulation of a turbulent clump of molecular hydrogen, with the densest areas shown in red. The zoom-in shows a protostar accreting gas and creating a dense wake behind it. The simulation shows that a protostar, once formed, cannot accrete much more gas from the surrounding clump, contradicting the competitive accretion theory. (Credit: Mark Krumholz)
Using supercomputer simulations that take into account the turbulence within a cloud collapsing to form a star, the researchers conclude that the "competitive accretion" model cannot explain what astronomers observe of star-forming regions studied to date.
That model, which is less than 10 years old and is championed by some British astronomers, predicts that interstellar hydrogen clouds develop clumps in which several small cores - the seeds of future stars - form. These cores, less than a light year across, collapse under their own gravity and compete for gas in the surrounding clump, often gaining 10 to 100 times their original mass from the clump.
Robert Sanders | EurekAlert!
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In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
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A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
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The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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