Measuring stellar oscillations with Kepler
The Kepler satellite is famous for its discovery of thousands of exoplanets by continuously and meticulously measuring the brightnesses of over half-a-million stars for the signatures of transiting exoplanets. Less well known are the revolutionary consequences of its monitoring program for stellar astrophysics, in particular for the study of stellar oscillations. Our own star, the sun, has been known since the 1960’s to exhibit oscillations, which are analogous to a bell’s ringing, as pressure waves generated by its rotation and internal structure circulate around its surface. The oscillations can be analyzed to reveal details of a star’s internal structures. Red giant stars, which are in a phase of stellar evolution after normal hydrogen burning is completed and have swelled in diameter, have been of particular interest because the oscillations in their surfaces are slower and of larger amplitude than in smaller stars, and hence easier to measure. Before the advent of space telescopes, however, even such measurements on red giants succeeded on only a few objects. The Kepler and Corot missions have since measured oscillations in thousands of red giant stars.
phys.org
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2019-09-04
