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Published July 2017 | Submitted + Published
Journal Article Open

Forecasting the Impact of Stellar Activity on Transiting Exoplanet Spectra


Exoplanet host star activity, in the form of unocculted starspots or faculae, alters the observed transmission and emission spectra of the exoplanet. This effect can be exacerbated when combining data from different epochs if the stellar photosphere varies between observations due to activity. Here, we present a method to characterize and correct for relative changes due to stellar activity by exploiting multi-epoch (⩾2 visits/transits) observations to place them in a consistent reference frame. Using measurements from portions of the planet's orbit where negligible planet transmission or emission can be assumed, we determine changes to the stellar spectral amplitude. With the analytical methods described here, we predict the impact of stellar variability on transit observations. Supplementing these forecasts with Kepler-measured stellar variabilities for F-, G-, K-, and M-dwarfs, and predicted transit precisions by the James Webb Space Telescope's (JWST) NIRISS, NIRCam, and MIRI, we conclude that stellar activity does not impact infrared transiting exoplanet observations of most presently known or predicted TESS targets by current or near-future platforms, such as JWST, as activity-induced spectral changes are below the measurement precision.

Additional Information

© 2017 American Astronomical Society. Received 2017 May 10. Accepted 2017 June 13. Published 2017 July 19. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. R.T.Z. would like to thank JPL's ExoSpec team and Jacob Bean for their insightful comments. We thank the referee for helpful comments. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. We thank the JPL Exoplanet Science Initiative for partial support of this work.

Attached Files

Published - Zellem_2017_ApJ_844_27.pdf

Submitted - 1705.04708.pdf


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