Plasma interactions of exoplanets with their parent star and associated radio emissions

Zarka, Philippe

doi:10.1016/j.pss.2006.05.045

Cited by 326 publications

(449 citation statements)

References 71 publications

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“…Thus, stellar irradiation could conceivably make it possible for electromotive moons to be detected in the magnetospheric plasma of hot Jupiters. Auroral radio emissions equivalent to non-Io-DAM will increase as well (Nichols 2011;Zarka 2007, and references therein), but given the differences in spectral signatures between Io-DAM and non-Io-DAM we do not expect these emissions to be a significant problem. Explicitly, exomoon signals should show long, thin arcs lasting several hours, like those on the simulated Io-DAM dynamic spectra shown on In general, we can say that an electromotive moon can obtain plasma from three different sources: (1) its own ionosphere, (2) the plasma torus of another moon, and (3) and its exoplanet's magnetospheric plasma.…”

Section: More Plasma Sourcesmentioning

confidence: 96%

On the Radio Detection of Multiple-Exomoon Systems Due to Plasma Torus Sharing

Noyola

Satyal

Musielak³

2016

ApJ

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The idea of single exomoon detection due to the radio emissions caused by its interaction with the host exoplanet is extended to multiple-exomoon systems. The characteristic radio emissions are made possible in part by plasma from the exomoon's own ionosphere. In this work, it is demonstrated that neighboring exomoons and the exoplanetary magnetosphere could also provide enough plasma to generate a detectable signal. In particular, the plasma-torus-sharing phenomenon is found to be particularly well suited to facilitate the radio detection of plasmadeficient exomoons. The efficiency of this process is evaluated, and the predicted power and frequency of the resulting radio signals are presented.

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Section: More Plasma Sourcesmentioning

confidence: 96%

On the Radio Detection of Multiple-Exomoon Systems Due to Plasma Torus Sharing

Noyola

Satyal

Musielak³

2016

ApJ

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“…On the stellar side, factors such as the thermal pressure, magnetic pressure (P B, ) and the ram pressure resulting from the relative motion between the planet and the coronal material can all contribute to setting the pressure equilibrium. The stellar-wind properties determine, for example, whether Earth-type magnetospheres surrounded by bow shocks or Ganymede-type magnetospheres with Alfvén wings are formed (Ip et al 2004;Zarka 2007;Kopp et al 2011;Sterenborg et al 2011;Saur et al 2013). To quantitatively evaluate this, the stellar wind density, temperature, magnetic field, and the relative velocity of the planet are required together with planetary magnetic characteristics.…”

Section: Interaction Between the Planet And The Corona Of Its Host Starmentioning

confidence: 99%

Effects of M dwarf magnetic fields on potentially habitable planets

Vidotto

Jardine

Morin

et al. 2013

A&A

152

161

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We investigate the effect of the magnetic fields of M dwarf (dM) stars on potentially habitable Earth-like planets. These fields can reduce the size of planetary magnetospheres to such an extent that a significant fraction of the planet's atmosphere may be exposed to erosion by the stellar wind. We used a sample of 15 active dM stars, for which surface magnetic-field maps were reconstructed, to determine the magnetic pressure at the planet orbit and hence the largest size of its magnetosphere, which would only be decreased by considering the stellar wind. Our method provides a fast means to assess which planets are most affected by the stellar magnetic field, which can be used as a first study to be followed by more sophisticated models. We show that hypothetical Earth-like planets with similar terrestrial magnetisation (∼1 G) orbiting at the inner (outer) edge of the habitable zone of these stars would present magnetospheres that extend at most up to 6 (11.7) planetary radii. To be able to sustain an Earth-sized magnetosphere, with the exception of only a few cases, the terrestrial planet would either (1) need to orbit significantly farther out than the traditional limits of the habitable zone; or else, (2) if it were orbiting within the habitable zone, it would require at least a magnetic field ranging from a few G to up to a few thousand G. By assuming a magnetospheric size that is more appropriate for the young-Earth (3.4 Gyr ago), the required planetary magnetic fields are one order of magnitude weaker. However, in this case, the polar-cap area of the planet, which is unprotected from transport of particles to/from interplanetary space, is twice as large. At present, we do not know how small the smallest area of the planetary surface is that could be exposed and would still not affect the potential for formation and development of life in a planet. As the star becomes older and, therefore, its rotation rate and magnetic field reduce, the interplanetary magnetic pressure decreases and the magnetosphere of planets probably expands. Using an empirically derived rotation-activity/magnetism relation, we provide an analytical expression for estimating the shortest stellar rotation period for which an Earth-analogue in the habitable zone could sustain an Earth-sized magnetosphere. We find that the required rotation rate of the early-and mid-dM stars (with periods 37-202 days) is slower than the solar one, and even slower for the late-dM stars ( 63-263 days). Planets orbiting in the habitable zone of dM stars that rotate faster than this have smaller magnetospheric sizes than that of the Earth magnetosphere. Because many late-dM stars are fast rotators, conditions for terrestrial planets to harbour Earth-sized magnetospheres are more easily achieved for planets orbiting slowly rotating early-and mid-dM stars.

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“…We put forward that this will open up the catalogue of potential candidates for detection of such kind of emission not only through the population of UCDs, but also among the exoplanets orbiting around stars of spectral type similar to our Sun. The possible exoplanetary auroral radio emission can be triggered by the interaction of the exoplanet magnetosphere with the radiatively-driven wind arising from the parent star (Zarka 2007). If we search for auroral radio emission from exoplanets with polar strengths similar to those of the magnetised planets in the solar system, the ECM emission process will operate in a frequency range that only SKA will cover with high sensitivity and resolution.…”

Section: Discussionmentioning

confidence: 99%

Probing the magnetosphere of the M8.5 dwarf TVLM 513−46546 by modelling its auroral radio emission. Hint of star exoplanet interaction?

Leto

Trigilio

Buemi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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In this paper we simulate the cyclic circularly-polarised pulses of the ultra-cool dwarf TVLM 513-46546, observed with the VLA at 4.88 and 8.44 GHz on May 2006, by using a 3D model of the auroral radio emission from the stellar magnetosphere. During this epoch, the radio light curves are characterised by two pulses left-hand polarised at 4.88 GHz, and one doubly-peaked (of opposite polarisations) pulse at 8.44 GHz. To take into account the possible deviation from the dipolar symmetry of the stellar magnetic field topology, the model described in this paper is also able to simulate the auroral radio emission from a magnetosphere shaped like an offset-dipole. To reproduce the timing and pattern of the observed pulses, we explored the space of parameters controlling the auroral beaming pattern and the geometry of the magnetosphere. Through the analysis of the TVLM 513-46546 auroral radio emission, we derive some indications on the magnetospheric field topology that is able to simultaneously reproduce the timing and patterns of the auroral pulses measured at 4.88 and 8.44 GHz. Each set of model solutions simulates two auroral pulses (singly or doubly peaked) per period. To explain the presence of only one 8.44 GHz pulse per period, we analyse the case of auroral radio emission limited only to a magnetospheric sector activated by an external body, like the case of the interaction of Jupiter with its moons.

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Plasma interactions of exoplanets with their parent star and associated radio emissions

Cited by 326 publications

References 71 publications

On the Radio Detection of Multiple-Exomoon Systems Due to Plasma Torus Sharing

On the Radio Detection of Multiple-Exomoon Systems Due to Plasma Torus Sharing

Effects of M dwarf magnetic fields on potentially habitable planets

Probing the magnetosphere of the M8.5 dwarf TVLM 513−46546 by modelling its auroral radio emission. Hint of star exoplanet interaction?

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