Convection zone
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A New Generation of Standard Solar Models Open
We compute a new generation of standard solar models (SSMs) that includes recent updates on some important nuclear reaction rates and a more consistent treatment of the equation of state. Models also include a novel and flexible treatment …
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Magnetic inhibition of convection and the fundamental properties of low-mass stars Open
When determining absolute ages of identifiably young stellar populations,\nresults strongly depend on which stars are studied. Cooler (K, M) stars\ntypically yield ages that are systematically younger than warmer (A, F, G)\nstars by a fact…
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Observational constraints on the origin of the elements Open
Context. The chemical composition of the Sun is required in the context of various studies in astrophysics, among them in the calculation of standard solar models (SSMs) used to describe the evolution of the Sun from the pre-main-sequence …
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The crucial role of surface magnetic fields for the solar dynamo Open
Sunspot cycle driven by linked fields Sunspots indicate magnetic flux emerging at the Sun's surface. Sunspots change over an 11-year time scale, which depends on the behavior of the probable magnetic dynamo within. Cameron et al. suggest t…
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MERIDIONAL CIRCULATION IN SOLAR AND STELLAR CONVECTION ZONES Open
We present a series of 3-D nonlinear simulations of solar-like convection, carried out using the Anelastic Spherical Harmonic (ASH) code, that are designed to isolate those processes that drive and shape meridional circulations within stel…
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On Differential Rotation and Overshooting in Solar-like Stars Open
We seek to characterize how the change of global rotation rate influences the overall dynamics and large-scale flows arising in the convective envelopes of stars covering stellar spectral types from early G to late K. We do so through nume…
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Observational constraints on the origin of the elements Open
Manganese (Mn) is a key Fe-group element, commonly employed in stellar population and nucleosynthesis studies to explore the role of SN Ia. We have developed a new non-local thermodynamic equilibrium (NLTE) model of Mn, including new photo…
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GRAND MINIMA AND EQUATORWARD PROPAGATION IN A CYCLING STELLAR CONVECTIVE DYNAMO Open
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 a model solar-mas…
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Turbulent convection and pulsation stability of stars – II. Theoretical instability strip for<i>δ</i>Scuti and<i>γ</i>Doradus stars Open
By using a non-local and time-dependent convection theory, we have calculated radial and low-degree non-radial oscillations for stellar evolutionary models with M = 1.4–3.0 M⊙. The results of our study predict theoretical instability …
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Nearly uniform internal rotation of solar-like main-sequence stars revealed by space-based asteroseismology and spectroscopic measurements Open
The rotation rates in the deep interior and at the surface of 22\nmain-sequence stars with masses between $1.0$ and $1.6\\,{\\rm M}_{\\odot}$ are\nconstrained by combining asteroseismological analysis with spectroscopic\nmeasurements. The …
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Seismic Sounding of Convection in the Sun Open
Thermal convection is the dominant mechanism of energy transport in the outer envelope of the Sun (one-third by radius). It drives global fluid circulations and magnetic fields observed on the solar surface. Vigorous surface convection exc…
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MERIDIONAL CIRCULATION IN THE SOLAR CONVECTION ZONE: TIME–DISTANCE HELIOSEISMIC INFERENCES FROM FOUR YEARS OF HMI/<i>SDO</i>OBSERVATIONS Open
We present and discuss results from time-distance helioseismic measurements\nof meridional circulation in the solar convection zone using 4 years of Doppler\nvelocity observations by the Helioseismic and Magnetic Imager (HMI) onboard the\n…
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H ingestion into He-burning convection zones in super-AGB stellar models as a potential site for intermediate neutron-density nucleosynthesis Open
We investigate the evolution of super-AGB (SAGB) thermal pulse (TP) stars for a range of metallicities (Z) and explore the effect of convective boundary mixing (CBM). With decreasing metallicity and evolution along the TP phase, the He-she…
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Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations Open
Is the Sun a solar-type star? The Sun's activity, including sun-spot activity, varies on an 11-year cycle driven by changes in its magnetic field. Other nearby solar-type stars have their own cycles, but the Sun does not seem to match thei…
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Multiple dynamo modes as a mechanism for long-term solar activity variations Open
Solar magnetic activity shows both smooth secular changes, such as the Grand Modern Maximum, and quite abrupt drops that are denoted as Grand Minima. Direct numerical simulations (DNS) of convection driven dynamos offer one way of examinin…
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Idealized hydrodynamic simulations of turbulent oxygen-burning shell convection in 4π geometry Open
This work investigates the properties of convection in stars with particular\nemphasis on entrainment across the upper convective boundary (CB). Idealised\nsimulations of turbulent convection in the O-burning shell of a massive star\nare p…
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ON THE ROLE OF TACHOCLINES IN SOLAR AND STELLAR DYNAMOS Open
Rotational shear layers at the boundary between radiative and convective zones, tachoclines, play a key role in the process of magnetic field generation in solar-like stars. We present two sets of global simulations of rotating turbulent c…
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A systematic study of proto-neutron star convection in three-dimensional core-collapse supernova simulations Open
This paper presents the first systematic study of proto-neutron star (PNS) convection in three dimensions (3D) based on our latest numerical fornax models of core-collapse supernova (CCSN). We confirm that PNS convection commonly occurs, a…
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Magnetic fields in non-convective regions of stars Open
We review the current state of knowledge of magnetic fields inside stars, concentrating on recent developments concerning magnetic fields in stably stratified (zones of) stars, leaving out convective dynamo theories and observations of con…
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Three-dimensional simulations of solar magneto-convection including effects of partial ionization Open
In recent decades, REALISTIC three-dimensional radiative-magnetohydrodynamic simulations have become the dominant theoretical tool for understanding the complex interactions between the plasma and magnetic field on the Sun. Most of such si…
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The i-process yields of rapidly accreting white dwarfs from multicycle He-shell flash stellar evolution models with mixing parametrizations from 3D hydrodynamics simulations Open
We have modelled the multicycle evolution of rapidly accreting CO white dwarfs (RAWDs) with stable H burning intermittent with strong He-shell flashes on their surfaces for 0.7 ≤ MRAWD/M⊙ ≤ 0.75 and [Fe/H] ranging from 0 to −2.6. We have a…
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MERIDIONAL FLOW IN THE SOLAR CONVECTION ZONE. II. HELIOSEISMIC INVERSIONS OF GONG DATA Open
Meridional flow is thought to play a very important role in the dynamics of the solar convection zone; however, because of its relatively small amplitude, precisely measuring it poses a significant challenge. Here we present a complete tim…
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CALIBRATION OF THE MIXING-LENGTH THEORY FOR CONVECTIVE WHITE DWARF ENVELOPES Open
A calibration of the mixing-length parameter in the local mixing-length\ntheory (MLT) is presented for the lower part of the convection zone in\npure-hydrogen atmosphere white dwarfs. The parameterization is performed from a\ncomparison of…
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On the surface physics affecting solar oscillation frequencies Open
Adiabatic oscillation frequencies of stellar models, computed with the standard mixing-length formulation for convection, increasingly deviate with radial order from observations in solar-like stars. Standard solar models overestimate adia…
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Thermo-compositional Diabatic Convection in the Atmospheres of Brown Dwarfs and in Earth’s Atmosphere and Oceans Open
By generalizing the theory of convection to any type of thermal and compositional source terms (diabatic processes), we show that thermohaline convection in Earth’s oceans, fingering convection in stellar atmospheres, and moist convection …
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A Review of the Mixing Length Theory of Convection in 1D Stellar Modeling Open
We review the application of the one-dimensional Mixing Length Theory (MLT) model of convection in stellar interiors and low-mass stellar evolution. We summarize the history of MLT, present a derivation of MLT in the context of 1D stellar …
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Relative importance of convective uncertainties in massive stars Open
In this work, we investigate the impact of uncertainties due to convective boundary mixing (CBM), commonly called ‘overshoot’, namely the boundary location and the amount of mixing at the convective boundary, on stellar structure and evolu…
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Convective overshoot and macroscopic diffusion in pure-hydrogen-atmosphere white dwarfs Open
We present a theoretical description of macroscopic diffusion caused by convective overshoot in pure-hydrogen DA white dwarfs using 3D, closed-bottom, radiation hydrodynamics co5bold simulations. We rely on a new grid of deep 3D white dwar…
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Solar inertial modes: Observations, identification, and diagnostic promise Open
The oscillations of a slowly rotating star have long been classified into spheroidal and toroidal modes. The spheroidal modes include the well-known 5-min acoustic modes used in helioseismology. Here we report observations of the Sun’s tor…
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BABCOCK–LEIGHTON SOLAR DYNAMO: THE ROLE OF DOWNWARD PUMPING AND THE EQUATORWARD PROPAGATION OF ACTIVITY Open
The key elements of the Babcock–Leighton dynamos are the generation of poloidal field through decay and the dispersal of tilted bipolar active regions and the generation of toroidal field through the observed differential rotation. These m…