Context. The quiet Sun presents magnetized plasma whose field strengths vary from zero to about 2 kG. The probability density function of the magnetic field strength B efficaciously describes the statistical properties of the quiet Sun magnetic field. Aims. We simulate the dynamics and the evolution of quiet Sun magnetic elements to produce a probability density function of the field strengths ...

1. INTRODUCTION " If the Sun had no magnetic field, it would be as uninteresting as most astronomers think it is. " This statement is attributed to R. B. Leighton (Moore and Rabin, 1985). Personally I think the Sun is of enormous interest in all respects, magnetic and non-magnetic; nonetheless, the grand challenges I have selected for this article do indeed pertain to the Sun's magnetic field. ...

Context. The quiet Sun presents magnetized plasma whose field strengths vary from zero to about 2 kG. The probability density function of the magnetic field strength B efficaciously describes the statistical properties of the quiet Sun magnetic field. Aims. We simulate the dynamics and the evolution of quiet Sun magnetic elements to produce a probability density function of the field strengths ...

We study the solar-cycle variations of solar p-mode travel time for different wave packets to probe the magnetic fields at the base of the solar convection zone. We select the wave packets which return to the same spatial point after traveling around the Sun with integral number of bounces. The change in onebounce travel time at solar maximum relative to minimum is approximately the same for al...

We present results from numerical modeling of emerging flux regions on the solar surface. The modeling was carried out by means of 3D radiative MHD simulations of the rise of buoyant magnetic flux tubes through the convection zone and into the photosphere. Due to the strong stratification of the convection zone, the rise results in a lateral expansion of the tube into a magnetic sheet, which ac...

The reliability of quiet Sun magnetic field diagnostics based on the Fe I lines at 6302 Å has been questioned by recent work. We present here the results of a thorough study of high-resolution multi-line observations taken with the new spectro-polarimeter SPINOR, comprising the 5250 and 6302 Å spectral domains. The observations were analyzed using several inversion algorithms, including Milne-E...

Turbulent convection in the solar photosphere can act as a small-scale dynamo, maintaining a disordered magnetic field that is locally intense. On the other hand, convection is inhibited in the presence of a strong, externally imposed magnetic field, as for instance, in a sunspot. Large-scale, three-dimensional, numerical experiments on highly nonlinear magnetoconvection in a Boussinesq fluid s...

We show that the use of Doppler shifts of Zeeman sensitive spectral lines to observe waves in sunspots is subject to measurement specific phase shifts arising from, (i) altered height range of spectral line formation and the propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening and splitting. We also show that these phase shifts depend on wave frequencies, strengths and...

Heavy oil is formed through biodegradation process of hydrocarbons, as well water washing, in which light hydrocarbon fraction disappears and leaves the heavy fraction. essentially an asphaltic, dense (low API gravity), viscous that chemically characterized by its high content asphaltenes oil. Although variously defi ned, 25o set upper limit for Central Sumatra Basin evidently a result washing ...

The implications of twist in active region magnetic elds is considered in this paper. The latitudinal distribution of twist that has been derived from recent vector magnetogram observations may be explained by the eeects of convective turbulence with a non-zero kinetic helicity acting on active region scale magnetic ux tubes as they rise through the convection zone. Highly twisted, kink unstabl...