Advances in asteroseismology with Kepler data
Stellar, Exoplanet and Galactic Science from Massive, High-precision Variability Surveys
Donald Kurtz
University of Central Lancashire
Hiromoto Shibahashi, Hideyuki Saio, Masao Takata, Simon Murphy, Timothy Bedding, Dominic Bowman, Takashi Sekii
1) We have discovered rotationally split core g-mode triplets and surface p-mode triplets and quintuplets two stars in the terminal age main sequence evolutionary phase. This gives the first robust determination of the rotation of the deep core and surface of a main sequence star, essentially model-independently. Our asteroseismic result, along with previous asteroseismic constraints on internal rotation in some B stars, and model-dependent measurements of internal rotation in some subgiant, giant and white dwarf stars, has made angular momentum transport in stars throughout their lifetimes an observational science. 2) There are many SPB stars and $\gamma$~Dor stars in the {\it Kepler} data set. Some of these stars show `frequency groups' in their amplitude spectra that have not previously been understood. We have unified the Fourier description of the light curves of these stars, showing that many of them can be understood in terms of only a few g~mode pulsations and combination frequencies, where sometimes a very large number of combination frequencies dominate the amplitude spectra. The frequency groups seen in these stars are thus tremendously simplified. Among the B stars are pulsating Be stars that show emission lines in their spectra from occasional ejection of material into a circumstellar disk. Our analysis gives strong support to the understanding of these pulsating Be stars as rapidly rotating SPB stars, explained entirely by g~mode pulsations.
13:30 - 15:00