Research for the Public

The Need for Supernova Simulations

Simulations, or numerical models, are 'what if' scenarios on the computer, designed to help scientists predict the outcomes of specific events. Simulations of stellar explosions have a rich history dating back to the 1950s, attempting to answer the question, "how do stars blow up"? Over the decades, scientists---Michael's research group included---have incorporated more accurate treatments of physics into their code to inch closer to the answer. While running simulations of stars blowing up is interesting in its own right, it raises the question, "how does this work help humanity in everyday life"? Fortunately, supernova research continuously pushes the development of world class supercomputers--technology that can also be used for topics ranging from cancer research to airplane design.

What Kind of Signal Can We Expect?

While theoretically researchers can predict gravitational waves (GWs) from exploding, massive stars, measuring them is a completely different challenge. International teams of scientists exist with extremely sensitive technology to detect GWs from the cosmos. However, the question stands, with the detection of GWs from a supernova, how much information would that reveal about its origin? Currently, Michael and his research group are working to decipher these signals and help isolate the key physics that contributes to stellar deaths. Some conclusions, so far, relate to the rotation of the supernova, the turbulence inside the explosion, and even peer back in time at what the star may have originally looked like.

The Last Heartbeat of a Massive Star

Historically, astrophysicists were limited to looking at just light when examining the cosmos. Telescopes work like 'light buckets' to collect light from the outer shell of stars and make a measurement. In September of 2015, the LIGO Scientific Collaboration changed the game as they detected gravitational waves (GWs) for the first time. GWs are ripples in the fabric of space and time that occur from very energetic events in the universe and can be thought of adding sound to the silent movie that was astronomy. When massive stars finish their life, they explode in a very energetic event called a supernova. These events also let off GWs that grant information about the physics that happens inside of the star. This new physics has the potential to improve science being done at national labs and offers valuable insight that can improve research in many areas of astronomy.

Right: One of Michael's simulations that models the inside of a star during a supernova explosion. The chaotic flow of material is partially responsible for emitting GWs.

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Stars Hiding in the Wrong Family Tree

There are crowded pockets of stars that orbit the Milky Way Galaxy called 'globular clusters'. When astronomers image these clusters, they can construct a family tree based on how red they appear and how bright they are (AKA a color magnitude diagram). While stars stay relatively stable for the majority of their lifetime, certain kinds can change their brightness and color---these are called variable stars. Because of these changes, certain types of variable stars can move off of their family tree and masquerade as belonging to different ones. In Michael's work, he helps determine that these stars can partially contribute to the illusion of multiple family trees when in reality, only one exists. Extremely powerful telescopes are needed to detect certain faint stars. This project then helps motivate engineering advances in telescope construction that, in turn, can contribute to more efficient computer systems and more sensitive cell phone cameras.

Right: A visualization of a variable star changing its color and brightness. (source gfycat)

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