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Astronomy Colloquium - "Connecting Magnets, Earthquakes, and Stars: Universal Avalanches Spanning 16 Decades in Length?"

Event Type
Astronomy Department
Astronomy 134
Dec 3, 2019   3:45 pm  
Dr. Karin Dahmen, U of Illinois
Rebecca Bare
Originating Calendar
Astronomy Colloquium Speaker Calendar
The star KIC8462852 (Tabby’s star) has shown anomalous drops in light flux. We perform a statistical analysis of the more numerous smaller dimming events by using methods found useful for avalanches in ferromagnetism and plastic flow [1]. Scaling exponents for avalanche statistics and temporal profiles of the flux during the dimming events are close to mean field predictions. Scaling collapses suggest that this star may be near a nonequilibrium critical point. The large events are interpreted as avalanches marked by modified dynamics, limited by the system size, and not within the scaling regime. Connections to other avalanching systems, including plastically deforming materials [2] and magnets [3] will also be discussed.
[1] Avalanche Statistics Identify Intrinsic Stellar Processes near Criticality in KIC 8462852
Mohammed A. Sheikh, Richard L. Weaver, and Karin A. Dahmen, Phys. Rev. Lett. 117, 261101 (2016).


[2] Universal Quake Statistics: From Compressed Nanocrystals to Earthquakes, Jonathan T. Uhl, Shivesh Pathak, Danijel Schorlemmer, Xin Liu, Ryan Swindeman, Braden A.W. Brinkman,, Michael LeBlanc, Georgios Tsekenis, Nir Friedman, Robert Behringer, Dmitry Denisov, Peter Schall, Xiaojun Gu, Wendelin J. Wright, Todd Hufnagel, Andrew Jennings, Julia R. Greer, P.K. Liaw, Thorsten Becker, Georg Dresen, and Karin A. Dahmen,  Scientific Reports 5, 16493 (2015).

[3] Crackling noise, James P. Sethna, Karin A. Dahmen & Christopher R. Myers, Nature 410, 242–250 (2001).
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