17 May 2012
17 May 2012
Speaker: Donald Kurtz (U. Central Lancashire)
Title:Asteroseismology: A New Keplerian Revolution
Abstract:In 1926 in the opening paragraph of his now-classic book, The Internal Constitution of the Stars, Sir Arthur Eddington lamented, \u201cWhat appliance can pierce through the outer layers of a star and test the conditions within?\u201d While he considered theory to be the proper answer to that question, there is now an observational answer: asteroseismology. We are in a time of a significant advance in our understanding of stellar astrophysics with data from the Kepler Mission, a space telescope orbiting the Sun on a mission to discover planets orbiting other stars. It has so far discovered more than 2200 exoplanets - the majority of all known - and is closing in on a goal to find another Earth in the \u201cGoldilocks zone\u201d where life might exist. Kepler has also improved our ability to see pulsations and variability in stars by 100 to 1000 times compared with ground-based telescopes, allowing us to see into stars using asteroseismology. We are seeing as never before: heartbeat stars, novel eclipsing stars, spots, flares and magnetic cycles as in our own Sun. Astrophysics that used to be theoretical is now also observational: gravitational lensing in eclipsing binary stars; Doppler boosting; multiple pulsation axes; period doubling; tidal excitation. Kepler data for solar-like stars are now comparable to data for the Sun seen as a star, giving us masses, radii and ages for hundreds of single stars, allowing determination of their orbiting planets\u2019 sizes, and giving new constraints on stellar evolution theory. This talk will introduce the concepts of asteroseismology and show a selection of exciting observational results from the Kepler mission. It will also introduce a new technique for measuring stellar radial velocities and the mass function from photometric light curves alone.