Scialog: Collaborative Teams - 2015
Physics, University of Arizona
Nuclear Burps and Belches: Presupernova Eruptions in 3D
Stars are the engines of creation. Understanding all phases of their long lives and ultimate, oft times explosive, demises can teach us a great deal about the behavior of matter under extreme conditions, as well as the nature of stars themselves.
Sean Couch, Michigan State, and Nathan Smith, University of Arizona, have received a Scialog award to increase our understanding of the nuclear “burps and belches” observed a few years before a massive star, many times larger than our sun, goes supernova. A titanic explosion many times brighter than an entire galaxy, a supernova occurs when a massive star runs out of nuclear fuel in its core and enters a rapid, gravitationally induced collapse.
Couch and Smith are interested in developing a three-dimensional computer model to test their theory about these complex precursor events. They have only been observed by astronomers on earth as the brightening and dimming of a few distant stars that subsequently went supernova.
Couch and Smith theorize the burps and belches occur due to the activity of convection (heat) plumes roiling among the shells – or layers -- of the dying star. Mature stars are thought to have a number of layers, somewhat like an onion, each dominated by a specific element, such as neon, oxygen or silicon, due to the interplay of billions of years of fusion, gravity and the unique density of each element.
The researchers theorize that nuclear burning, a process by which lighter elements such as helium are fused into heavier elements such as iron, occurs in one shell, creating plumes of rising superhot matter and general turbulence that invade lighter, or higher, shells. As this hot mess falls back into the burning shell, they suspect, the process works to pull in even more fuel, causing the massive eruptions astronomers have glimpsed as changes in luminosity.
These changes are thought to signify titanic releases of energy and matter into space -- a dire warning of impending supernova.