Time-dependent hydrodynamical simulations of slow solar wind,
 coronal inflows, and polar plumes

Pinto, Rui; Grappin, R.; Wang, Y.-M.; Léorat, J.

doi:10.1051/0004-6361/200811183

Cited by 30 publications

(38 citation statements)

References 24 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Faster wind velocities require a complete and consistent energetic treatment, which is beyond the scope of the current paper. Besides, Pinto et al (2009) show that the anti-correlation between terminal wind velocity and flux-tube expansion factor is still verified in self-consistent nonisothermal cases. The only strong constraint over the domain's radial extent regarding the physical correctness of the numerical model is that it has to completely contain all critical surfaces (sonic and Alfvénic; cf.…”

Section: Solar Wind Speedmentioning

confidence: 78%

“…The choice of a particular value for the coronal temperature is somewhat arbitrary, though. The temperature T = 1.3 MK chosen here is justified both by representing an average coronal value in the first ∼10 R (see, e.g., results by Hansteen & Leer 1995;Endeve et al 2003;Guhathakurta et al 2006;Pinto et al 2009, among others) and empirically as it produces correct wind solutions. As discussed later in the text, the wind's mass flux depends both on the coronal temperature and on wind geometrical expansion factors.…”

Section: Dip: Wind Modelmentioning

confidence: 99%

“…Hansteen & Leer (1995) showed that the mass flux does not depend strongly on the mode and location of energy deposition, but rather on the amplitude of the energy flux. Note also that the heat flux profile could be related to the magnetic field's amplitude and geometry (Cranmer et al 2007;Pinto et al 2009). The resulting angular momentum losses and wind's braking torque (applied on the Sun) depend on wind's velocity and mass flux together with the (time-varying) geometry of the Alfvén surface (the surface at which the wind's velocity equals the Alfvén velocity; see definitions in Section 5).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coupling the Solar Dynamo and the Corona: Wind Properties, Mass, and Momentum Losses During an Activity Cycle

Pinto

Brun

Jouve

et al. 2011

ApJ

113

View full text Add to dashboard Cite

We study the connections between the Sun's convection zone and the evolution of the solar wind and corona. We let the magnetic fields generated by a 2.5-dimensional (2.5D) axisymmetric kinematic dynamo code (STELEM) evolve in a 2.5D axisymmetric coronal isothermal magnetohydrodynamic code (DIP). The computations cover an 11 year activity cycle. The solar wind's asymptotic velocity varies in latitude and in time in good agreement with the available observations. The magnetic polarity reversal happens at different paces at different coronal heights. Overall the Sun's mass-loss rate, momentum flux, and magnetic braking torque vary considerably throughout the cycle. This cyclic modulation is determined by the latitudinal distribution of the sources of open flux and solar wind and the geometry of the Alfvén surface. Wind sources and braking torque application zones also vary accordingly.

show abstract

Section: Solar Wind Speedmentioning

confidence: 78%

Section: Dip: Wind Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coupling the Solar Dynamo and the Corona: Wind Properties, Mass, and Momentum Losses During an Activity Cycle

Pinto

Brun

Jouve

et al. 2011

ApJ

113

View full text Add to dashboard Cite

show abstract

“…The effect of these temperature variations could perhaps be simulated in our model by setting a non-uniform coronal T 0 (varying in latitude and in time), but -as discussed above -the distribution of fast and slow wind flows is the outcome of the model, on which its parameters cannot depend. An in-depth investigation of the thermodynamics of the solar wind flows requires a different kind of model (as in Suzuki & Inutsuka 2006;Pinto et al 2009;Woolsey & Cranmer 2014), which will be the subject of future work. Nevertheless, the approach we adopt here strongly suggests that the absolute values and spatial distribution of the solar wind speed is mostly controlled by the geometry of the coronal magnetic field (independently of the heating scenario considered).…”

Section: Discussionmentioning

confidence: 99%

“…Suzuki (2006), in particular, suggests that the wind speed should scale as V wind ∝ B 0 / f tot (keeping the coronal temperature and the wave power input constant). The amplitude of the magnetic field and the way it decays with height can also influence the rate and position at which this energy input is dissipated in the corona, which in turn affects the terminal wind speed (see Pinto et al 2009;Cranmer 2002, and many others). Alternatively, one can interpret this relationship between wind speed and B 0 / f tot as resulting from a conjugation of geometrical properties of the coronal magnetic field.…”

Section: Wind Speed Expansion and Magnetic Field Amplitudementioning

confidence: 99%

Flux-tube geometry and solar wind speed during an activity cycle

Pinto

Brun

Rouillard

2016

A&A

View full text Add to dashboard Cite

Context. The solar wind speed at 1 AU shows cyclic variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal (asymptotic) wind speed in a given magnetic flux-tube is generally anti-correlated with its total expansion ratio, which motivated the definition of widely used semiempirical scaling laws relating one to the other. In practice, such scaling laws require ad hoc corrections (especially for the slow wind in the vicinities of streamer/coronal hole boundaries) and empirical fits to in situ spacecraft data. A predictive law based solely on physical principles is still missing. Aims. We test whether the flux-tube expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes (close to and far from streamer boundaries) using a very large sample of wind-carrying open magnetic flux-tubes. We furthermore search for additional physical parameters based on the geometry of the coronal magnetic field which have an influence on the terminal wind flow speed. Methods. We use numerical magneto-hydrodynamical simulations of the corona and wind coupled to a dynamo model to determine the properties of the coronal magnetic field and of the wind velocity (as a function of time and latitude) during a whole 11-yr activity cycle. These simulations provide a large statistical ensemble of open flux-tubes which we analyse conjointly in order to identify relations of dependence between the wind speed and geometrical parameters of the flux-tubes which are valid globally (for all latitudes and moments of the cycle). Results. Our study confirms that the terminal (asymptotic) speed of the solar wind depends very strongly on the geometry of the open magnetic flux-tubes through which it flows. The total flux-tube expansion is more clearly anti-correlated with the wind speed for fast rather than for slow wind flows, and effectively controls the locations of these flows during solar minima. Overall, the actual asymptotic wind speeds attained -especially those of the slow wind -are also strongly dependent on field-line inclination and magnetic field amplitude at the foot-points. We suggest ways of including these parameters in future predictive scaling laws for the solar wind speed.

show abstract

The very slow solar wind: Properties, origin and variability

et al. 2016

View full text Add to dashboard Cite

Solar wind slower than 300 km/s, hereafter termed very slow solar wind (VSSW), is seldom observed at 1 AU. It was, however, commonly measured inside 0.7 AU by the two Helios spacecraft, particularly during solar maximum. Magnetohydrodynamic (MHD) modeling reveals that the disappearance of VSSW at 1 AU is the result of its interaction with faster solar wind. The acceleration and compression of the VSSW contributes to the observed highly variable structure of the slow solar wind at 1 AU. The VSSW usually contains the heliospheric plasma sheet and current sheet. It has higher density and lower temperature than the regular slow solar wind, extending the known scaling laws below 300 km/s. Its helium abundance increases with solar activity even more significantly than the slow solar wind. Contrary to faster solar winds, the helium ions in the VSSW are slower than the dominant protons. Combining a Potential Field Source Surface (PFSS) model with ballistic back tracing, we study the source region of the VSSW. We show that the proton density flux for the VSSW is much higher than for the faster winds, particularly at solar maximum.

show abstract

Time-dependent hydrodynamical simulations of slow solar wind, coronal inflows, and polar plumes

Cited by 30 publications

References 24 publications

Coupling the Solar Dynamo and the Corona: Wind Properties, Mass, and Momentum Losses During an Activity Cycle

Coupling the Solar Dynamo and the Corona: Wind Properties, Mass, and Momentum Losses During an Activity Cycle

Flux-tube geometry and solar wind speed during an activity cycle

The very slow solar wind: Properties, origin and variability

Contact Info

Product

Resources

About