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Northwestern University


CIERA Lunches 2016-2017

Lunches are held at 12:00 PM on Mondays in Room F160
 on the first floor of the Technological Institute (2145 Sheridan Road).

Pizza will be provided unless otherwise noted.

 

Spring Quarter 2017

  Date/Time      Visitor Host
  April 17
 

Daniel Lecoanet
    Princeton University
         Measuring Core Stellar Magnetic Fields using Wave Conversion

By studying oscillation modes at the surface of stars, astrophysicists are able to infer characteristics of their deep interior structure. This was first applied to observations of the Sun, but recently space-based telescopes have measured oscillations in many other stars, leading to new mysteries in stellar structure and evolution. Recent work has suggested that low dipole oscillation amplitudes in red giant branch stars may indicate strong core magnetic fields. Here we present both numerical simulations and analytic calculations of the interactions of waves with a strong magnetic field. We can solve the problem very accurately by using the WKB approximation to reduce the 2D PDE into a series of ODEs for each height. We find that magnetic fields convert the buoyancy-driven waves observable at the surface of the star to magnetic waves, which are not present at the surface, in agreement with observations.

Yoram Lithwick

 

Fall Quarter 2016

  Date/Time      Visitor Host
  Oct. 10
 

Steven Jacobsen
    Northwestern University, Earth and Planetary Sciences
    Earth's deep water cycle: atomic to geophysical scales

Yoram Lithwick
  Oct. 31
  

Magdalena Osburn
    Northwestern University, Earth and Planetary Sciences
    Life Underground — Understanding life strategies of Earth’s intraterrestrials to better
    search for extraterrestrials

Yoram Lithwick

For more information, contact: ciera@northwestern.edu