Department of Physics and Astronomy
Clemson University, Kinard Lab of Physics, G01, Lecture Hall
Thursday, February 1, 2018, 4:00 pm
Dr. Jordi Bustamante
Oak Ridge National Laboratory
Multi-dimensional Simulations of Mixing in Classical Novae
Abstract: Classical novae are explosive phenomena that take place in stellar binary systems. They are powered by mass transfer from a low-mass, main sequence star onto a white dwarf. The material piles up under degenerate conditions until a thermonuclear runaway ensues. The energy released by the suite of nuclear processes operating at the envelope heats the material up to peak temperatures about (0.1-0.4) GK. During these events, material enriched in CNO and other intermediate-mass elements, are ejected into the interstellar medium. To account for the gross observational properties of classical novae (in particular, a metallicity enhancement in the ejecta above solar values), 1D models often assume mixing between the (solar-like) material transferred from the companion and the outermost layers (CO- or ONe-rich) of the underlying white dwarf. The origin of the large enhancements and inhomogeneous distribution of chemical species observed in high-resolution spectra of ejected nova shells has, however, remained unexplained for almost half a century. I will present multi-D simulations of classical novae with the FLASH code, and will discuss the role of Kelvin-Helmholtz instabilities as a natural mechanism for self-enrichment of the accreted envelope with core material. Such mixing also naturally produces large-scale chemical inhomogeneities. Both the metallicity enhancement and the intrinsic dispersions in the abundances are consistent with the observed values.
Bio sketch: Dr. Bustamante is a theoretical astrophysicist interested in understanding the nature of stellar explosions, such as classical novae and core-collapse supernovae. He received his PhD in Astrophysics in 2011 from the Technical University of Catalonia. He focuses on understanding the mixing processes operating at the core-envelope interface, and how the convective front progresses in nova outbursts. In 2012, he moved to NC State University as a postdoc and started working on core-collapse supernovae, as well as continuing to work on novae. As a postdoc at ORNL he performs multi-dimensional hydrodynamic simulations to study the interplay between turbulence and the dynamics of the explosion during a supernova event."
Refreshments will be served after the presentation in the P&A Café.
Thursday, February 1 at 4:00pm to 5:00pm
Kinard Laboratory of Physics, G01 Kinard Lab
140 Delta Epsilon Ct., Clemson, SC 29634, USA