A magnetic mechanism for halting inward protoplanet migration: I. Necessary conditions and angular momentum transfer timescales

Fleck, Robert

doi:10.1007/s10509-007-9703-5

Cited by 10 publications

(4 citation statements)

References 38 publications

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“…In the extreme case where the travel time of alfvénic perturbations is short compared to the orbital period (see Eq. 2), the waves can propagate back and forth between the planet location and the stellar surface and the effective area of interaction is the full Alfvén wing from the planet location to the stellar surface (see also Fleck 2008). In general, though, the effective obstacle will be only composed of a subpart of the Alfvén wings (see Figure 5 in Strugarek 2016).…”

Section: Numerical Modelsmentioning

confidence: 99%

Models of Star-Planet Magnetic Interaction

Strugarek¹

2017

Handbook of Exoplanets

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Magnetic interactions between a planet and its environment are known to lead to phenomena such as aurorae and shocks in the solar system. The large number of close-in exoplanets that were discovered triggered a renewed interest in magnetic interactions in star-planet systems. Multiple other magnetic effects were then unveiled, such as planet inflation or heating, planet migration, planetary material escape, and even modification of the host star properties. We review here the recent efforts in modelling and understanding magnetic interactions between stars and planets in the context of compact systems. We first provide simple estimates of the effects of magnetic interactions and then detail analytical and numerical models for different representative scenarii. We finally lay out a series of future developments that are needed today to better understand and constrain these fascinating interactions.

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Section: Numerical Modelsmentioning

confidence: 99%

Models of Star-Planet Magnetic Interaction

Strugarek¹

2017

Handbook of Exoplanets

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“…The effective area of interaction in SPMI has been a widely used concept in the past years (see, e.g. Lovelace et al 2008;Fleck 2008;Vidotto et al 2014;Bouvier & Cébron 2015, and references therein). It is generally viewed as an effective obstacle area A eff , and is often approximated by a magnetospheric size obtained from a simple pressure balance between the planetary magnetosphere and the wind pressure which gives…”

Section: Effective Area Of the Interactionmentioning

confidence: 99%

Assessing Magnetic Torques and Energy Fluxes in Close-in Star–planet Systems

Strugarek

2016

ApJ

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Planets in close-in orbit interact with the magnetized wind of their hosting star. This magnetic interaction was proposed to be a source for enhanced emissions in the chromosphere of the star, and to participate in setting the migration time-scale of the close-in planet. The efficiency of the magnetic interaction is know to depend on the magnetic properties of the host star, of the planet, and on the magnetic topology of the interaction. We use a global, three-dimensional numerical model of closein star planet systems, based on the magnetohydrodynamics approximation, to compute a grid of simulations for varying properties of the orbiting planet. We propose a simple parametrization of the magnetic torque that applies to the planet, and of the energy flux generated by the interaction. The dependancy upon the planet properties and the wind properties are clearly identified in the derived scaling laws, which can be used in secular evolution codes to take into account the effect of magnetic interactions in planet migration. They can also be used to estimate a potential magnetic source of enhanced emissions in observed close-in star-planet systems, in order to constrain observationally possible exoplanetary magnetic fields. Subject headings: planets and satellites: dynamical evolution and stability -planet-star interactions -stars: wind, outflows -magnetohydrodynamics (MHD)

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“…Exoplanet migration may be influenced by the stellar wind plasma, as well as by how the stellar magnetosphere interacts with the disc. Simulations [209], and analytic work [70,156], suggest that the inner disc hole, cleared by the star-disc interaction, may provide a natural barrier that decreases the rate of inward migration of forming planets. However, if a multipolar magnetosphere were to be considered, the structure of columns of accreting gas within the magnetospheric gap may alter the migration rate of planets [209].…”

Section: Summary and Applications To Outstanding Problemsmentioning

confidence: 99%

The magnetic fields of forming solar-like stars

Gregory¹,

Jardine²,

Gray³

et al. 2010

Rep. Prog. Phys.

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Magnetic fields play a crucial role at all stages of the formation of low-mass stars and planetary systems. In the final stages, in particular, they control the kinematics of in-falling gas from circumstellar discs, and the launching and collimation of spectacular outflows. The magnetic coupling with the disc is thought to influence the rotational evolution of the star, while magnetized stellar winds control the braking of more evolved stars and may influence the migration of planets. Magnetic reconnection events trigger energetic flares which irradiate circumstellar discs with high energy particles that influence the disc chemistry and set the initial conditions for planet formation. However, it is only in the past few years that the current generation of optical spectropolarimeters has allowed the magnetic fields of forming solar-like stars to be probed in unprecedented detail. In order to do justice to the recent extensive observational programs new theoretical models are being developed that incorporate magnetic fields with an observed degree of complexity. In this review we draw together disparate results from the classical electromagnetism, molecular physics/chemistry and the geophysics literature, and demonstrate how they can be adapted to construct models of the large scale magnetospheres of stars and planets. We conclude by examining how the incorporation of multipolar magnetic fields into new theoretical models will drive future progress in the field through the elucidation of several observational conundrums.(Some figures in this article are in colour only in the electronic version) 3.4. Difference between a spherical and Cartesian tensor approach 13 4. Magnetospheric accretion models with multipolar magnetic fields 14 4.1. Development of PFSS models and comparison with MHD field extrapolations 14 4.2. Potential field models of T Tauri magnetospheres with complex fields 16 4.3. 3D MHD models of T Tauri magnetospheres with non-dipolar fields 18 5. Summary and applications to outstanding problems 19 Acknowledgments 21 Appendix A. Relations between the equatorial and polar field strength for a multipole of arbitrary order l 21 Appendix A.1. Odd-order multipoles 21 Appendix A.2. Even-order multipoles 22 Appendix B. Electrostatic expansion using Cartesian tensors 22 Appendix B.1. The dipole term 23 Appendix B.2. The quadrupole term 23 References 24

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A magnetic mechanism for halting inward protoplanet migration: I. Necessary conditions and angular momentum transfer timescales

Cited by 10 publications

References 38 publications

Models of Star-Planet Magnetic Interaction

Models of Star-Planet Magnetic Interaction

Assessing Magnetic Torques and Energy Fluxes in Close-in Star–planet Systems

The magnetic fields of forming solar-like stars

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