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Forecasting the Impact of Stellar Activity on Transiting Exoplanet Spectra

Zellem, Robert T. and Swain, Mark R. and Roudier, Gael and Shkolnik, Evgenya L. and Creech-Eakman, Michelle J. and Ciardi, David R. and Line, Michael R. and Iyer, Aishwarya R. and Bryden, Geoffrey and Llama, Joe and Fahy, Kristen A. (2017) Forecasting the Impact of Stellar Activity on Transiting Exoplanet Spectra. Astrophysical Journal, 844 (1). Art. No. 27. ISSN 1538-4357.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zellem, Robert T.0000-0001-7547-0398
Swain, Mark R.0000-0002-0919-4468
Shkolnik, Evgenya L.0000-0002-7260-5821
Ciardi, David R.0000-0002-5741-3047
Line, Michael R.0000-0002-2338-476X
Llama, Joe0000-0003-4450-0368
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.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:methods: analytical; planets and satellites: atmospheres; planets and satellites: detection; stars: activity; starspots
Issue or Number:1
Record Number:CaltechAUTHORS:20170803-075702003
Persistent URL:
Official Citation:Robert T. Zellem et al 2017 ApJ 844 27
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79812
Deposited By: Ruth Sustaita
Deposited On:05 Aug 2017 20:59
Last Modified:09 Mar 2020 13:19

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