The operation of the solar global dynamo appears to involve many dynamical elements, including generation fields by intense turbulence deep convection zone, transport these into tachocline region near base storage and amplification toroidal in differential rotation, destabilization emergence such due magnetic buoyancy. Self-consistent magnetohydrodynamic (MHD) simulations that realistically incorporate all processes are not yet computationally feasible, although some elements can now be...

▪ Abstract Helioseismology has transformed our knowledge of the Sun's rotation. Earlier studies revealed surface rotation, but now a detailed observational picture been built up internal rotation nearest star. Unlike predictions stellar-evolution models, radiative interior is found to rotate roughly uniformly. The within convection zone also very different from prior expectations, which had that rate would depend primarily on distance axis. Layers rotational shear have discovered at base and...

The past few decades have seen dramatic progress in our understanding of solar interior dynamics, prompted by the relatively new science helioseismology and increasingly sophisticated numerical models. As ultimate driver variability space weather, global-scale convective motions are particular interest from a practical as well theoretical perspective. Turbulent convection under influence rotation stratification redistributes momentum energy, generating differential rotation, meridional...

Rotationally constrained convection possesses velocity correlations that transport momentum and drive mean flows such as differential rotation. The nature of this can be very complex in turbulent flow regimes, where large-scale, coherent vorticity structures established by smaller scale turbulence through inverse cascades. dynamics the highly solar zone therefore may quite different than early global-scale numerical models, which were limited computational resources to nearly laminar flows....

Three-dimensional simulations of solar convection in spherical shells are used to evaluate the differential rotation that results as thermal boundary conditions varied. In some a latitudinal entropy variation is imposed at lower order take into account coupling between convective envelope and radiative interior through wind balance tachocline. The issue whether baroclinic forcing arising from tachocline-induced variations can break tendency for numerical yield cylindrical profiles, unlike...

The global scales of solar convection are studied through three-dimensional simulations compressible carried out in spherical shells rotating fluid that extend from the base zone to within 15 Mm photosphere. Such modeling at highest spatial resolution date allows study distinctly turbulent convection, revealing coherent downflow structures associated with giant cells continue play a significant role maintaining differential rotation is achieved. These lower latitudes exhibit prograde...

Young solar-type stars rotate rapidly and many are magnetically active; some undergo magnetic cycles similar to the 22-year solar activity cycle. We conduct simulations of dynamo action in rotating suns with 3D MHD anelastic spherical harmonic (ASH) code explore achieved convective envelope a star at 5 times current rotation rate. Striking global-scale wreaths appear midst turbulent convection zone show rich time-dependence. The exhibits cyclic undergoes quasi-periodic polarity reversals...

When our Sun was young it rotated much more rapidly than now. Observations of young, rotating stars indicate that many possess substantial magnetic activity and strong axisymmetric fields. We conduct simulations dynamo action in suns with the 3-D MHD anelastic spherical harmonic (ASH) code to explore complex coupling between rotation, convection magnetism. Here we study realized bulk zone for a system at three times current solar rotation rate. find organized global-scale fields are achieved...

We present the first results from three-dimensional spherical shell simulations of magnetic dynamo action realized by turbulent convection penetrating downward into a tachocline rotational shear. This permits us to assess several dynamical elements believed be crucial operation solar global dynamo, variously involving differential rotation resulting convection, pumping, and amplification fields stretching within tachocline. The reveal that strong axisymmetric toroidal (about 3000 G in...

Stars can be fascinating settings in which to study intricate couplings among convection, rotation, magnetism, and shear, usually under distinctly nonlinear conditions that yield vigorous turbulence. The emerging flux the rotation rates of stars vary widely, yet there are common elements must contribute building maintaining vibrantly evolving magnetic activity they exhibit. Some these elements, such as rotational shear meridional flows established by coupling convection with now studied...

Solar-type stars exhibit a rich variety of magnetic activity. Seeking to explore the convective origins this activity, we have carried out series global 3D magnetohydrodynamic (MHD) simulations with anelastic spherical harmonic (ASH) code. Here report on dynamo mechanisms achieved as effects artificial diffusion are systematically decreased. The at nominal rotation rate three times solar value (3$Ω_\odot$), but similar dynamics may also apply Sun. Our previous demonstrated that dynamos can...

The global dynamics of a rotating star like the Sun involves coupling highly turbulent convective envelope overlying seemingly benign radiative interior. We use anelastic spherical harmonic code to develop new class three-dimensional models that nonlinearly couple deep stable numerical simulation assumes realistic solar stratification from r = 0.07 up 0.97R (with R radius), thus encompassing part nuclear core through most convection zone. find tachocline naturally establishes itself between...

The 3-D magnetohydrodynamic (MHD) Anelastic Spherical Harmonic (ASH) code, using slope-limited diffusion, is employed to capture convective and dynamo processes achieved in a global-scale stellar convection simulation for model solar-mass star rotating at three times the solar rate. generated magnetic fields possesses many time scales, with prominent polarity cycle occurring roughly every 6.2 years. field forms large-scale toroidal wreaths, whose formation tied low Rossby number of this...

We present a series of 3D nonlinear simulations solar-like convection, carried out using the Anelastic Spherical Harmonic code, that are designed to isolate those processes drive and shape meridional circulations (MCs) within stellar convection zones. These have been constructed so as span transition between differential rotation (DR; fast equator/slow poles) "anti-solar" DR (slow equator/fast poles). Solar-like states DR, which arise when is rotationally constrained, characterized by very...

view Abstract Citations (182) References (61) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Statistical Analysis of Turbulence in Molecular Clouds Miesch, Mark S. ; Bally, John We present an investigation the statistical properties fluctuating gas motions five nearby molecular clouds using two-point autocorrelation and structure functions power spectra their radial velocity as traced by emission-line centroid velocities. Our analysis includes observations...

In the solar convection zone, rotation couples with intensely turbulent to drive a strong differential and achieve complex magnetic dynamo action. Our sun must have rotated more rapidly in its past, as is suggested by observations of many rotating young solar-type stars. Here we explore effects rapid on global-scale patterns such stars flows meridional circulation which are self-consistently established. The these systems richly time dependent our most suns striking pattern localized...

We conside the kinetics near a first-order poisoning transition for simple surface reaction models which exlude nonreactive desorption. Elucidation of development and growth reactive steady state from near-poisoned is achieved via an ``oxidation epidemic'' analysis evolution empy patch embedded in poisoned phase. Associated critical exponents vary strongly with rate, reflect slow kinetics. The increase epidemic survival probability initial size smooth, described by additional exponents,...

We use global and local helioseismic inversions to explore the prevailing dynamical balances in solar near-surface shear layer (NSSL). The differential rotation meridional circulation are intimately linked, with a common origin turbulent stresses of upper convection zone. existence structure NSSL cannot be attributed solely conservation angular momentum by surface convection, as is often supposed. Rather, transport accounts for poleward flow while overlooked force balance required maintain...

Our global 3D simulations of convection and dynamo action in a Sun-like star reveal that persistent wreaths strong magnetism can be built within the bulk convention zone. Here we examine characteristics buoyant magnetic structures are self-consistently created by turbulent convective motions simulation with solar stratification but rotating at three times current rate. These loops originate sections which flows amplify fields to much larger values than is possible through laminar processes....

We present a 3D kinematic solar dynamo model in which poloidal field is generated by the emergence and dispersal of tilted sunspot pairs (more generally Bipolar Magnetic Regions, or BMRs). The axisymmetric component this functions similarly to previous 2D Babcock-Leighton (BL) models that employ double-ring prescription for generation but we generalize into flux algorithm places BMRs on surface response dynamo-generated toroidal field. In way, can be regarded as unification BL (2D...