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dc.contributor.authorVidotto, A. A.
dc.contributor.authorJardine, M.
dc.contributor.authorHelling, Ch.
dc.identifier.citationVidotto , A A , Jardine , M & Helling , C 2010 , ' Early UV ingress in WASP-12b: measuring planetary magnetic fields ' , Astrophysical Journal Letters , vol. 722 , no. 2 , pp. L168-L172 .
dc.identifier.otherPURE: 4968303
dc.identifier.otherPURE UUID: 671c6089-b309-4c72-a578-e81a8692b563
dc.identifier.otherWOS: 000282909200009
dc.identifier.otherScopus: 78649238545
dc.identifier.otherBibCode: 2010ApJ...722L.168V
dc.identifier.otherORCID: /0000-0002-1466-5236/work/57821903
dc.description.abstractRecently, Fossati et al. observed that the UV transit of WASP-12b showed an early ingress compared with the optical transit. We suggest that the resulting early ingress is caused by a bow shock ahead of the planetary orbital motion. In this Letter, we investigate the conditions that might lead to the formation of such a bow shock. We consider two scenarios: (1) the stellar magnetic field is strong enough to confine the hot coronal plasma out to the planetary orbit and (2) the stellar magnetic field is unable to confine the plasma, which escapes in a wind. In both cases, a shock capable of compressing plasma to the observed densities will form around the planet for plasma temperatures T less than or similar to (4-5) x 10(6) K. In the confined case, the shock always forms directly ahead of the planet, but in the wind case the shock orientation depends on the wind speed and hence on the plasma temperature. For higher wind temperatures, the shock forms closer to the line of centers between the planet and the star. We conclude that shock formation leading to an observable early UV ingress is likely to be a common feature of transiting systems and may prove to be a useful tool in setting limits on planetary magnetic field strengths B-p. In the case of WASP-12b, we derive an upper limit of about B-p = 24 G.
dc.relation.ispartofAstrophysical Journal Lettersen
dc.rights© 2010. The American Astronomical Society. All rights reserved.en
dc.subjectPlanet-star interactionsen
dc.subjectPlanets and satellites: individual (WASP-12b)en
dc.subjectPlanets and satellites: magnetic fieldsen
dc.subjectStars: coronaeen
dc.subjectStars: individual (WASP-12)en
dc.subjectStars: winds, outflowsen
dc.subjectExtrasolar planeten
dc.subjectQC Physicsen
dc.titleEarly UV ingress in WASP-12b: measuring planetary magnetic fieldsen
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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