Thanks to a supercomputer in Texas, astronomers solved a big mystery about why stars form.
Space is vast and there's a lot of empty space between stars. In that empty space are a lot of massive clouds made of hydrogen molecules. When those clouds condense, stars start forming. However, only a small portion of those molecules actually become stars. But previous computer simulations show that nearly all of those molecules form stars, which is not the case.
This is the mystery that once plagued astrophysicists. Now, however, thanks to the Stampede supercomputer of the Texas Advanced Computing Center, an Extreme Science and Engineering Discovery Environment-allocated resource funded by the National Science Foundation, a team of astrophysicists solved that mystery.
Those simulations show that the activity of stars, such as starlight emission and supernova explosions, is crucial in the formation of other stars, as well as the growth of galaxies.
"Feedback from stars, the collective effects from supernovae, radiation, heating, pushing on gas, and stellar winds can regulate the growth of galaxies and explain why galaxies have turned so little of the available supply of gas that they have into stars," says theoretical astrophysicist Philip Hopkins.
Researchers put Stampede to work by creating new small-scale galaxy models with the supercomputer. They began with simulating single stars and then grew that to full galaxy simulations. The idea was to put what they know about physics into a simulation of the clouds of hydrogen that birth stars.
These simulations were so realistic that they surprised researchers, especially since they were easily put together. Previous models required a lot of tweaking after each run.
"My real jaw-dropping moment," says Hopkins, "was when we put the physics that we thought had been missing from the previous models in without giving ourselves a bunch of knobs to turn. We ran it and it actually looked like a real galaxy. And it only had a few percent of material that turned into stars, instead of all of it, as in the past."
Hopkins hopes that the same simulation could be used to explore what happens in those "oddball" galaxies, the ones with strange sizes and masses and other unique properties. He also wants to simulate galaxies similar to our own, those with supermassive black holes at the center. These sort of simulations were impossible previously, but new supercomputers like Stampede, which run a record-breaking thousands of CPUs at any given time on these new simulations, have made the impossible now possible.
[Photo Credit: Texas Advanced Computing Center]