Vampire Stars and the (Re)Birth of Blue Stragglers

Seminar Date:
October 25th, 2012

Speaker:
Dr. Aaron Geller
Lindheimer Fellow
Northwestern University

Title:
Vampire Stars and the (Re)Birth of Blue Stragglers

Abstract:
Blue stragglers are stars that somehow maintain a "youthful", bright and blue appearance while their counterparts of similar mass grow old and die.  Current formation hypotheses for blue stragglers include mass transfer in binaries, mergers of binaries, and stellar collisions.  The origins of blue stragglers tie together many fundamental areas of stellar astrophysics.  Therefore blue stragglers are ideal test subjects to verify the accuracy of binary evolution models and star cluster simulations.  However despite the more than 50 years of research on blue stragglers, their dominant formation mechanism(s) remains a matter of debate, in part due to a lack of direct observational evidence that can distinguish between the formation channels.  In this talk, I will present our detailed observations coupled with N-body numerical models of the blue stragglers in the old open cluster NGC 188. Our results point to a blue straggler origin in "stellar vampirism".  

This research also offers fantastic opportunities for visualizations. The detailed theoretical models and simulations are both educational and visually engaging (and well suited for Planetarium shows!).  I will present a sample of the visualizations that I have developed and used to educate students and the public about blue stragglers, binary stars, stellar evolution and the dynamical evolution of star clusters.