We use 2D numerical simulations and eikonal approximation, to study properties of MHD waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different magnetic field strengths, from 10 Mm below the photosphere to the low chromosphere. The purpose of these studies is to quantify the effect of the magnetic fi...

We reexamine closely the solar photospheric line at 6300 Å, which is attributed to a forbidden line of neutral oxygen, and is widely used in analyses of other latetype stars. We use a three-dimensional time-dependent hydrodynamical model solar atmosphere which has been tested successfully against observed granulation patterns and an array of absorption lines. We show that the solar line is a bl...

The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes with a non-potential field structure that are located in intergranular lanes. With a typical horizontal size of 200 km at the base of the photosphere, they expand upward and merge with their neighbors at a he...

We outline a general methodology to infer the inductive velocity field vector in solar active regions. For the first time, both the field-aligned and the crossfield velocity components are reconstructed. The cross-field velocity solution accounts for the changes of the vertical magnetic field seen between a pair of successive active-region vector magnetograms via the ideal induction equation. T...

We use a flux transport model to simulate the evolution of the Sun’s total and open magnetic flux over the last 26 solar cycles (1713–1996). Polar field reversals are maintained by varying the meridional flow speed between 11 and 20 m s , with the poleward-directed surface flow being slower during low-amplitude cycles. If the strengths of the active regions are fixed but their numbers are taken...

We revisit the distant future of the Sun and the Solar system, based on stellar models computed with a thoroughly tested evolution code. For the solar giant stages, mass loss by the cool (but not dust-driven) wind is considered in detail. Using the new and well-calibrated mass-loss formula of Schröder & Cuntz, we find that the mass lost by the Sun as a red giant branch (RGB) giant (0.332 M , 7....

The properties and dynamics of magnetic fields on the Sun’s photosphere and outer layers – notably those within solar active regions – govern the eruptive activity of the Sun. These photospheric magnetic fields also act as the evolving lower boundary of the Sun-Earth coupled system. Quantifying the physical attributes of these magnetic fields and exploring the mechanisms underlying their influe...

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3 nm line taken with the CRisp Imaging Spectro-Polarimeter at the Swedish 1 m Solar Telescope. We compute Dopplergrams from the observed intensity profiles usi...

Kilogauss-strength magnetic fields are often observed in intergranular lanes at the photosphere in the quiet Sun. Such fields are stronger than the equipartition field Be, corresponding to a magnetic energy density that matches the kinetic energy density of photospheric convection, and comparable with the field Bp that exerts a magnetic pressure equal to the ambient gas pressure. We present an ...

Aims. We describe a new form of small-scale magnetic flux emergence in the quiet Sun. This process seems to take vertical magnetic fields from the solar interior to the photosphere, where they appear above granular convection cells. Methods. High-cadence time series of spectropolarimetric measurements obtained by Hinode in a quiet region near disk center are analyzed. We extract line parameters...