FM17p.13 — Systematics-insensitive periodograms with K2 and the detection of exoplanets orbiting evolved stars

Date & Time

Aug 10th at 6:00 PM until 6:00 PM




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Author(s): Ruth Angus3, John Johnson1, Daniel Foreman-Mackey2

Institution(s): 1. Harvard-Smithsonian Center for Astrophysics, 2. New York University, 3. University of Oxford

Systematic features in K2 light curves, caused by decreased spacecraft pointing precision, pollute the periodograms of long-cadence asteroseismic targets. We develop a method to produce periodograms of K2 light curves that are insensitive to pointing-induced systematics. By modelling light curves as a combination of the systematic trends shared across all stars, as well as a sum of sine and cosine functions over a grid of frequencies, we are able to model the systematics and signals of interest simultaneously. This systematics-insensitive method produces periodograms free from systematic features and, crucially, removes the 6-hour thruster firing signal. We demonstrate that the quality of the resulting periodograms are such that we can detect asteroseismic oscillations in giants without the need for any detrending. In addition, we develop a method for increasing the detectability of exoplanets orbiting evolved stars, based on their oscillation frequencies.