Can the Solar Wind Be Driven by Magnetic Reconnection in the Sun's Magnetic Carpet?

Cranmer, Steven R.; Ballegooijen, A. A. van

doi:10.1088/0004-637x/720/1/824

Cited by 78 publications

(86 citation statements)

References 155 publications

(265 reference statements)

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“…For example, it could be that the solar wind is heated by the dissipation of Alfvén waves whereas the solar corona is heated by magnetic reconnection events (Cranmer & van Ballegooijen 2010). Furthermore, Cohen (2011) pointed out that while the solar X-ray luminosity, L X , varies by over an order of magnitude during the solar cycle, the mass loss rate does not change in any significant way, and suggested therefore that the mass loss rates of other stars are independent of their X-ray properties.…”

Section: Scaling Base Temperaturementioning

confidence: 99%

Stellar winds on the main-sequence

Johnstone

Güdel

Lüftinger

et al. 2015

A&A

100

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Aims. We develop a method for estimating the properties of stellar winds for low-mass main-sequence stars between masses of 0.4 M and 1.1 M at a range of distances from the star. Methods. We use 1D thermal pressure driven hydrodynamic wind models run using the Versatile Advection Code. Using in situ measurements of the solar wind, we produce models for the slow and fast components of the solar wind. We consider two radically different methods for scaling the base temperature of the wind to other stars: in Model A, we assume that wind temperatures are fundamentally linked to coronal temperatures, and in Model B, we assume that the sound speed at the base of the wind is a fixed fraction of the escape velocity. In Paper II of this series, we use observationally constrained rotational evolution models to derive wind mass loss rates. Results. Our model for the solar wind provides an excellent description of the real solar wind far from the solar surface, but is unrealistic within the solar corona. We run a grid of 1200 wind models to derive relations for the wind properties as a function of stellar mass, radius, and wind temperature. Using these results, we explore how wind properties depend on stellar mass and rotation. Conclusions. Based on our two assumptions about the scaling of the wind temperature, we argue that there is still significant uncertainty in how these properties should be determined. Resolution of this uncertainty will probably require both the application of solar wind physics to other stars and detailed observational constraints on the properties of stellar winds. In the final section of this paper, we give step by step instructions for how to apply our results to calculate the stellar wind conditions far from the stellar surface.

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Section: Scaling Base Temperaturementioning

confidence: 99%

Stellar winds on the main-sequence

Johnstone

Güdel

Lüftinger

et al. 2015

A&A

100

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“…On the other hand, such interactions have been treated in local models "resolving" only a small portion of the solar surface. (Parnell 2001;Simon et al 2001;Rast 2003;Crouch et al 2007;Cranmer & van Ballegooijen 2010;Meyer et al 2011). These processes are highly non-linear, with smaller structures aggregating to form larger ones, and larger structures disintegrating into smaller ones, making models complex and computationally demanding.…”

Section: Introductionmentioning

confidence: 99%

Solar Photospheric Network Properties and Their Cycle Variation

Thibault

Charbonneau

Béland

2014

ApJ

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We present a numerical simulation of the formation and evolution of the solar photospheric magnetic network over a full solar cycle. The model exhibits realistic behavior as it produces large, unipolar concentrations of flux in the polar caps, a power-law flux distribution with index −1.69, a flux replacement timescale of 19.3 hr, and supergranule diameters of 20 Mm. The polar behavior is especially telling of model accuracy, as it results from lower-latitude activity, and accumulates the residues of any potential modeling inaccuracy and oversimplification. In this case, the main oversimplification is the absence of a polar sink for the flux, causing an amount of polar cap unsigned flux larger than expected by almost one order of magnitude. Nonetheless, our simulated polar caps carry the proper signed flux and dipole moment, and also show a spatial distribution of flux in good qualitative agreement with recent high-latitude magnetographic observations by Hinode. After the last cycle emergence, the simulation is extended until the network has recovered its quiet Sun initial condition. This permits an estimate of the network relaxation time toward the baseline state characterizing extended periods of suppressed activity, such as the Maunder Grand Minimum. Our simulation results indicate a network relaxation time of 2.9 yr, setting 2011 October as the soonest the time after which the last solar activity minimum could have qualified as a Maunder-type Minimum. This suggests that photospheric magnetism did not reach its baseline state during the recent extended minimum between cycles 23 and 24.

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“…Previous studies of the small-scale coronal field, using either observed or synthetic magnetograms as the lower-boundary condition, include those of van Ballegooijen et al (1998), Schrijver & Title (2002), Close et al (2003), Close et al (2004), Parnell (2009), andvan Ballegooijen (2010). A limitation of the above studies is that they consider only potential magnetic fields and independent extrapolations of the coronal field for each magnetogram.…”

Section: Introductionmentioning

confidence: 99%

THE STORAGE AND DISSIPATION OF MAGNETIC ENERGY IN THE QUIET SUN CORONA DETERMINED FROM SDO /HMI MAGNETOGRAMS

Meyer

Sabol

Mackay

et al. 2013

ApJ

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In recent years, higher cadence, higher resolution observations have revealed the quiet-Sun photosphere to be complex and rapidly evolving. Since magnetic fields anchored in the photosphere extend up into the solar corona, it is expected that the small-scale coronal magnetic field exhibits similar complexity. For the first time, the quiet-Sun coronal magnetic field is continuously evolved through a series of non-potential, quasi-static equilibria, deduced from magnetograms observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, where the photospheric boundary condition which drives the coronal evolution exactly reproduces the observed magnetograms. The build-up, storage, and dissipation of magnetic energy within the simulations is studied. We find that the free magnetic energy built up and stored within the field is sufficient to explain small-scale, impulsive events such as nanoflares. On comparing with coronal images of the same region, the energy storage and dissipation visually reproduces many of the observed features. The results indicate that the complex small-scale magnetic evolution of a large number of magnetic features is a key element in explaining the nature of the solar corona.

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Can the Solar Wind Be Driven by Magnetic Reconnection in the Sun's Magnetic Carpet?

Cited by 78 publications

References 155 publications

Stellar winds on the main-sequence

Stellar winds on the main-sequence

Solar Photospheric Network Properties and Their Cycle Variation

THE STORAGE AND DISSIPATION OF MAGNETIC ENERGY IN THE QUIET SUN CORONA DETERMINED FROM SDO /HMI MAGNETOGRAMS

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