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Zarka, Philippe; Treumann, R. A.; Ryabov, B. P.; Ryabov, V. B.

doi:10.1023/a:1012221527425

Cited by 182 publications

(214 citation statements)

References 20 publications

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“…Grießmeier et al (2004Grießmeier et al ( , 2005Grießmeier et al ( , 2007 investigate SPI with particular emphasis on the radio emission from extrasolar planets and their detectability from Earth depending on various parameters such as stellar wind properties. Zarka et al (2001), Zarka (2006Zarka ( , 2007, and Hess & Zarka (2011) also investigate the plasma interaction of extrasolar planets with their parent star and their associated putative radio emission. Li et al (1998), Willes & Wu (2004, and Hess & Zarka (2011) study the possible electromagnetic coupling of extrasolar planets around white dwarfs and their effects on radio emission and orbital evolution.…”

Section: Introductionmentioning

confidence: 99%

Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions

Saur

Grambusch

Duling

et al. 2013

A&A

176

332

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Context. Electromagnetic coupling of planetary moons with their host planets is well observed in our solar system. Similar couplings of extrasolar planets with their central stars have been studied observationally on an individual as well as on a statistical basis. Aims. We aim to model and to better understand the energetics of planet star and moon planet interactions on an individual and as well as on a statistical basis. Methods. We derived analytic expressions for the Poynting flux communicating magnetic field energy from the planetary obstacle to the central body for sub-Alfvénic interaction. We additionally present simplified, readily useable approximations for the total Poynting flux for small Alfvén Mach numbers. These energy fluxes were calculated near the obstacles and thus likely present upper limits for the fluxes arriving at the central body. We applied these expressions to satellites of our solar system and to HD 179949 b. We also performed a statistical analysis for 850 extrasolar planets. Results. Our derived Poynting fluxes compare well with the energetics and luminosities of the satellites' footprints observed at Jupiter and Saturn. We find that 295 of 850 extrasolar planets are possibly subject to sub-Alfvénic plasma interactions with their stellar winds, but only 258 can magnetically connect to their central stars due to the orientations of the associated Alfvén wings. The total energy fluxes in the magnetic coupling of extrasolar planets vary by many orders of magnitude and can reach values larger than 10 19 W. Our calculated energy fluxes generated at HD 179949 b can only explain the observed energy fluxes for exotic planetary and stellar magnetic field properties. In this case, additional energy sources triggered by the Alfvén wave energy launched at the extrasolar planet might be necessary. We provide a list of extrasolar planets where we expect planet star coupling to exhibit the largest energy fluxes. As supplementary information we also attach a table of the modeled stellar wind plasma properties and possible Poynting fluxes near all 850 extrasolar planets included in our study. Conclusions. The orders of magnitude variations in the values for the total Poynting fluxes even for close-in extrasolar planets provide a natural explanation why planet star coupling might have been only observable on an individual basis but not on a statistical basis.

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Section: Introductionmentioning

confidence: 99%

Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions

Saur

Grambusch

Duling

et al. 2013

A&A

176

332

View full text Add to dashboard Cite

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“…The stellar magnetic pressure is therefore the dominant pressure term of the wind in the HZ. In contrast, the ram pressure dominates in the HZ of solar-type stars (Zarka et al 2001;Zarka 2007;Jardine & Collier Cameron 2008) and so we limit ourselves to studying the stellar wind ram pressure term in this paper. A&A 570, A99 (2014) In order to study the interaction between stellar winds and exoplanets, we use a survey of 167 stars observed by the Bcool Collaboration (Marsden et al 2014).…”

Section: Introductionmentioning

confidence: 99%

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

See

Jardine

Vidotto

et al. 2014

A&A

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Context. The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However, the planet's magnetosphere should also be considered, since without it, an exoplanet's atmosphere may be eroded away by stellar winds. Aims. The aim of this paper is to investigate magnetospheric protection of a planet from the effects of stellar winds from solar-mass stars. Methods. We study hypothetical Earth-like exoplanets orbiting in the host star's habitable zone for a sample of 124 solar-mass stars. These are targets that have been observed by the Bcool Collaboration. Using two wind models, we calculate the magnetospheric extent of each exoplanet. These wind models are computationally inexpensive and allow the community to quickly estimate the magnetospheric size of magnetised Earth-analogues orbiting cool stars. Results. Most of the simulated planets in our sample can maintain a magnetosphere of ∼5 Earth radii or larger. This suggests that magnetised Earth analogues in the habitable zones of solar analogues are able to protect their atmospheres and is in contrast to planets around young active M dwarfs. In general, we find that Earth-analogues around solar-type stars, of age 1.5 Gyr or older, can maintain at least a Paleoarchean Earth sized magnetosphere. Our results indicate that planets around 0.6-0.8 solar-mass stars on the low activity side of the Vaughan-Preston gap are the optimum observing targets for habitable Earth analogues.

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“…Surprisingly, the conversion efficiency between incident and emitted power is roughly constant for every planet. This relation is encapsulated by the radiometric Bode's law (Desch & Kaiser 1984;Farrell et al 1999;Zarka et al 2001;Zarka 2007) with Jupiter having the strongest radio emission of the solar system planets.…”

Section: Introductionmentioning

confidence: 99%

Time-scales of close-in exoplanet radio emission variability

See

Jardine

Farès

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and τ Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetised hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is co-rotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of τ Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of the magnetic cycle. The lack of radio variability on the synodic period at τ Boo b is not predicted by previous radio emission models, which do not account for the co-rotation of the interplanetary plasma at small distances from the star.

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Untitled

Cited by 182 publications

References 20 publications

Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions

Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

Time-scales of close-in exoplanet radio emission variability

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