Aspects of the magnetosphere–stellar wind interaction of close-in extrasolar planets

Grießmeier, Jean-Mathias

doi:10.1016/j.pss.2006.11.003

Cited by 9 publications

(5 citation statements)

References 179 publications

(542 reference statements)

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“…Radio emission from the Tau Bootis b system hasn't been detected yet, even though we find, in agreement with several former studies (e.g. Farrell et al 2003;Lazio & Farrell 2007;Grießmeier et al 2005Grießmeier et al , 2006bGrießmeier 2007;Grießmeier et al 2007bGrießmeier et al ,a, 2011, that it should be a good candidate for successful observations. Radio fluxes were predicted to be in the sensitivity range of several radio telescopes, e.g.…”

Section: Implications For Future Observation Campaigns Targeting Tau ...supporting

confidence: 91%

Supermassive hot Jupiters provide more favourable conditions for the generation of radio emission via the cyclotron maser instability – a case study based on Tau Bootis b

Weber

Еркаев

Иванов

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We investigate under which conditions supermassive hot Jupiters can sustain source regions for radio emission, and whether this emission could propagate to an observer outside the system. We study Tau Bootis b-like planets (a supermassive hot Jupiter with 5.84 Jupiter masses and 1.06 Jupiter radii), but located at different orbital distances (between its actual orbit of 0.046 AU and 0.2 AU). Due to the strong gravity of such planets and efficient radiative cooling, the upper atmosphere is (almost) hydrostatic and the exobase remains very close to the planet, which makes it a good candidate for radio observations. We expect similar conditions as for Jupiter, i.e. a region between the exobase and the magnetopause that is filled with a depleted plasma density compared with cases where the whole magnetosphere cavity is filled with hydrodynamically outward flowing ionospheric plasma. Thus, unlike classical hot Jupiters like the previously studied planets HD 209458b and HD 189733b, supermassive hot Jupiters should be in general better targets for radio observations.

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Section: Implications For Future Observation Campaigns Targeting Tau ...supporting

confidence: 91%

Supermassive hot Jupiters provide more favourable conditions for the generation of radio emission via the cyclotron maser instability – a case study based on Tau Bootis b

Weber

Еркаев

Иванов

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…As far as eq. ( 1) is concerned, the final rotation rate ω f can be neglected, at least for the planets of interest in this work (Grießmeier, 2006).…”

Section: Final Rotation Rate ω Fmentioning

confidence: 99%

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Grießmeier

Stadelmann

Grenfell

et al. 2009

Icarus

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Previous studies have shown that extrasolar Earth-like planets in close-in habitable zones around M-stars are weakly protected against galactic cosmic rays (GCRs), leading to a strongly increased particle flux to the top of the planetary atmosphere. Two main effects were held responsible for the weak shielding of such an exoplanet: (a) For a close-in planet, the planetary magnetic moment is strongly reduced by tidal locking. Therefore, such a close-in extrasolar planet is not protected by an extended magnetosphere. (b) The small orbital distance of the planet exposes it to a much denser stellar wind than that prevailing at larger orbital distances. This dense stellar wind leads to additional compression of the magnetosphere, which can further reduce the shielding efficiency against GCRs. In this work, we analyse and compare the effect of (a) and (b), showing that the stellar wind variation with orbital distance has little influence on the cosmic ray shielding. Instead, the weak shielding of M star planets can be attributed to their small magnetic moment. We further analyse how the planetary mass and composition influence the planetary magnetic moment, and thus modify the cosmic ray shielding efficiency. We show that more massive planets are not necessarily better protected against galactic cosmic rays, but that the planetary bulk composition can play an important role.

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“…If the planet mass is known, a fast rotation speed of the planet could suggest the presence of a significant magnetic field. One must note, however, that there will be a large list of caveats to this possibility, given our current understanding of dynamos and planetary evolution (Bushby & Mason 2004;Grie%meier 2007).…”

Section: Introductionmentioning

confidence: 99%

Identifying the Rotation Rate and the Presence of Dynamic Weather on Extrasolar Earth‐like Planets from Photometric Observations

Πάλλη

Ford

Seager

et al. 2008

ApJ

123

126

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With the recent discoveries of hundreds of extrasolar planets, the search for planets like Earth and life in the universe is quickly gaining momentum. In the future, large space observatories could directly detect the light scattered from rocky planets, but they would not be able to spatially resolve a planet's surface. Using reflectance models and real cloud data from satellite observations, here we show that, despite Earth's dynamic weather patterns, the light scattered by the Earth to a hypothetical distant observer as a function of time contains sufficient information to accurately measure Earth's rotation period. This is because ocean currents and continents result in relatively stable averaged global cloud patterns. The accuracy of these measurements will vary with the viewing geometry and other observational constraints. If the rotation period can be measured with accuracy, data spanning several months could be coherently combined to obtain spectroscopic information about individual regions of the planetary surface. Moreover, deviations from a periodic signal can be used to infer the presence of relatively short-lived structures in its atmosphere (i.e., clouds). This could provide a useful technique for recognizing exoplanets that have active weather systems, changing on a timescale comparable to their rotation. Such variability is likely to be related to the atmospheric temperature and pressure being near a phase transition and could support the possibility of liquid water on the planet's surface.

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Aspects of the magnetosphere–stellar wind interaction of close-in extrasolar planets

Abstract: Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detaillierte bibliografische Daten sind im Internet über http://dnb.ddb.de abrufbar.

Cited by 9 publications

References 179 publications

Supermassive hot Jupiters provide more favourable conditions for the generation of radio emission via the cyclotron maser instability – a case study based on Tau Bootis b

Supermassive hot Jupiters provide more favourable conditions for the generation of radio emission via the cyclotron maser instability – a case study based on Tau Bootis b

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Identifying the Rotation Rate and the Presence of Dynamic Weather on Extrasolar Earth‐like Planets from Photometric Observations

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