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dc.contributor.authorLlama, Joe
dc.contributor.authorShkolnik, E. L.
dc.identifier.citationLlama , J & Shkolnik , E L 2015 , ' Transiting the Sun : the impact of stellar activity on X-ray and ultraviolet transits ' , Astrophysical Journal , vol. 802 , no. 1 .
dc.identifier.otherPURE: 240750071
dc.identifier.otherPURE UUID: 750af279-a3b5-406c-836e-fda4c6465798
dc.identifier.otherBibCode: 2015ApJ...802...41L
dc.identifier.otherScopus: 84925815818
dc.descriptionThis work is supported by NASA Origins of the Solar System grant No. NNX13AH79G.en
dc.description.abstractTransits of hot Jupiters in X-rays and the ultraviolet have been shown to be both deeper and more variable than the corresponding optical transits. This variability has been attributed to hot Jupiters having extended atmospheres at these wavelengths. Using resolved images of the Sun from NASA’s Solar Dynamics Observatory spanning 3.5 yr of Solar Cycle 24 we simulate transit light curves of a hot Jupiter to investigate the impact of Solar-like activity on our ability to reliably recover properties of the planet’s atmosphere in soft X-rays (94 Å), the UV (131-1700 Å), and the optical (4500 Å). We find that for stars with activity levels similar to those of the Sun, the impact of stellar activity results in underestimating the derived radius of the planet in soft X-ray/EUV by up-to 25% or overestimating it by up to 50% depending on whether the planet occultsactive regions. We also find that in up to 70% of the X-ray light curves the planet transits over bright starspots. In the far-ultraviolet (1600 Å and 1700 Å), we find the mean recovered value of Rp/R* to be over-estimated by up to 20%. For optical transits we are able to consistently recover the correct planetary radius. We also address the implications of our results for transits of WASP-12 b and HD 189733b at short wavelengths.
dc.relation.ispartofAstrophysical Journalen
dc.rights© 2015. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at
dc.subjectPlanets and satellites: atmospheresen
dc.subjectPlanets and satellites: individual: HD 189733ben
dc.subjectStars: activityen
dc.subjectStars: coronaeen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleTransiting the Sun : the impact of stellar activity on X-ray and ultraviolet transitsen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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