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| Titel |
Magnetic communication in extrasolar planetary systems |
| VerfasserIn |
Andreas Kopp, Bernd Heber, Klaus Scherer, Horst Fichtner |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042375
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| Zusammenfassung |
| Hot Jupiters revolve around their host stars on very close orbits within a few days. This
vicinity between star and planet leads to features unknown from the solar system, the most
interesting of which is their magnetic interaction. The latter is manifested by a so-called
hotspot in the stellar atmosphere moving across the stellar disk with the orbital
period of the planet, which is phase-shifted with respected to the substellar point. A
possible explanation for this phenomenon can be found by applying the Jupiter-Io
scenario to these systems: the planetary ionosphere perturbs the stellar magnetic field.
While this perturbation propagates in form of a field-aligned electric current along
the Alfvén characteristics towards the star, the planet continues its orbit, so that
an observer sees the transits of hotspot and planet at different times. Adopting a
Weber-Davis model for the stellar wind, we can explain the observed phase shifts of
all five planetary systems known so far to show such a behaviour: HDÂ 179949,
HD 189733, HD 192263, Ï Boo A, and Ï
 And. We support our findings by numerical
simulations of the field-aligned current system evolving between planet and star. The
stellar parameters derived from fitting the model to the observed phase angles,
moreover, allows to estimate the stellar winds and, thus, the astrospheres around these
stars. |
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