For more information about this meeting, contact Toan Nguyen, Fei Wang, Hope Shaffer, Jinchao Xu.

Title: | Instability theory of gaseous stars |

Seminar: | CCMA PDEs and Numerical Methods Seminar Series |

Speaker: | Ian Tice, Carnegie Mellon University |

Abstract Link: | http://www.math.cmu.edu/math/faculty/Tice |

Abstract: |

A simple astrophysical model of stars considers them to be a
compact mass of self-gravitating compressible fluid. Such a fluid obeys
the compressible Navier-Stokes-Poisson equations. In the case of
"polytropic gases," in which the pressure behaves like
$P = K \rho^\gamma$ for $K>0$ an entropy constant and $\gamma >1$ an
adiabatic constant, one may construct compactly supported, finite mass,
radially symmetric equilibrium solutions by reducing to the Lane-Emden
ODE (at least when $6/5 < \gamma < 2$). A fundamental question in
astrophysics is the stability of such equilibria, and it was believed
that they should be unstable for $6/5 < \gamma < 4/3$ and stable for
$4/3 \le \gamma < 2$. In this talk we will prove that the
Navier-Stokes-Poisson system, perturbed around a Lane-Emden equilibrium
configuration, is nonlinearly unstable when $6/5 < \gamma < 4/3$. This
is joint work with Juhi Jang. |

### Room Reservation Information

Room Number: | MB106 |

Date: | 04 / 11 / 2014 |

Time: | 02:30pm - 03:30pm |