Institute for Computational Astrophysics
Image of the Month
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The interaction of turbulent convection and radial stellar pulsation remains one of the more challenging problems in stellar astrophysics. Dr. Chris Geroux, former Ph. D. student in the ICA and currently a postdoctoral fellow at the University of Exeter, and Dr. Robert Deupree are addressing this issue with 2D and 3D hydrodynamic simulations of RR Lyrae variable stars. Performing the calculations in more than one dimension allows the inclusion of at least the large scale convective flow rather than relying on a formulaic procedure to impose a time dependent behavior of convection. They previously showed that 2D simulations matched RR Lyrae light curves quite well (see November 2012 image of the month). However, the convective energy transport in the turbulent outer layers of these stars is clearly 3D in nature, and the 2D calculations have now been extended to 3D.
The variation in the pulsation amplitude with location in the instability strip is shown for both the 2D and 3D calculations and observational data from Cacciari et al. (2005) for the RR Lyrae stars in the globular cluster M3. The open symbols refer to the data, the red symbols to the 2D simulations, and the blue symbols to the 3D simulations. Circles refer to fundamental mode pulsators and squares to first overtone pulsators. The 2D and 3D amplitudes agree rather well, although some of the 3D amplitudes are somewhat below their 2D counterparts. Work is in progress to examine this difference. Both sets of simulations agree reasonably well with the data, particularly since no effort was made to fine tune the input physics to the individual cluster. A comparison of the light curves for individual stars and specific 2D and 3D models is under way.
Introduction to ICA
The Institute for Computational Astrophysics (ICA) was formed to expand an area of expertise within the Department of Astronomy and Physics at Saint Mary's University. Since its creation in late 2001, the ICA has grown to six full time faculty members, and at any time there are on the order of eight graduate students and two post doctoral fellows amongst the ICA membership. This does not include the other faculty, graduate students, and post doctoral fellows in the Department of Astronomy and Physics. The ICA promotes research in computational astrophysics through the research and publication activities of the individual members, by hosting visitors and colloquium speakers, and by having all its members participate in national and international conferences.
The ICA is also responsible for providing its members with access to high performance computing resources. The ICA has its own small cluster for code development, but most computing is done through ACEnet, the academic research high performance computing provider for Atlantic Canada. ACEnet also provides other collaboration and visualization tools on the Saint Mary's campus. The ICA has played a significant role in the formation and direction of ACEnet, with one ICA member serving as the Principal Investigator of ACEnet since the project was funded, two others having served or currently serving on the Research Directorate, and one member on the Resource Allocation Committee. ACEnet also employs three full time technical support personnel stationed at Saint Mary's, and ICA members have been major beneficiaries of their expertise.
News & Events
- Michael Gruberbauer successfully defended his Ph.D. thesis
- Data Cave Art Show and Lecture: 3D art exhibition presented by Lisa Frank
- Ph.D. student James Wurster has accepted a postdoctoral position at Monash University in Australia
- Former ICA post-doc Dr Pascal Elahi has accepted a position at University of Sydney in Australia.
- Chris Geroux successfully defended his Ph. D. thesis
- Dave Williamson successfully defended his Ph. D. thesis
- Anneya Golob successfully defended her M.Sc. thesis
- Dr. Mike Casey has accepted a research position at the Bedford Institute of Oceanography.
- Stephen Condran, ACEnet System Administrator for the Brasdor cluster, has joined SMU ACEnet staff.
- Ph. D. student Chris Geroux has accepted a postdoctoral position with Dr. Isabelle Baraffe at the University of Exeter.