Recent observations of coronal-loop waves by TRACE and within the corona as a whole by CoMP clearly indicate that the dominant oscillation period is 5 minutes, thus implicating the solar p modes as a possible source. We investigate the generation of tube waves within the solar convection zone by the buffeting of p modes. The tube waves—in the form of longitudinal sausage waves and transverse ki...

We report on 3.6 cm VLA and VLBA observations of YZ CMi and AD Leo, two nearby dMe stars. We resolve YZ CMi and can fit a circular symmetrical gaussian component of FWHP of 0.98 ±0.2 mas, corresponding to an extent of the corona above the photosphere of 1.77 × 1010 ± 8.8 × 109 cm or 0.7 ±0.3 R? (R? refers to the photospheric radius). We obtain an estimate of the brightness temperature of 7.3 × ...

We present a detailed investigation of the dynamical behavior of emerging magnetic flux using 3dimensional MHD numerical simulation. A magnetic flux tube with a lefthanded twist, initially placed below the photosphere, emerges into the solar atmosphere. This leads to a dynamical expansion of emerging field lines as well as an injection of magnetic energy and magnetic helicity into the atmospher...

The MHD virial theorem may be used to estimate the magnetic energy of active regions based on vector magnetic fields measured at the photosphere or chromosphere. However, the virial estimate depends on the measured vector magnetic field being forcefree. Departure from force-freeness leads to an unknown systematic error in the virial energy estimate, and an origin dependence of the result. We pr...

The ANTARES radiation hydrodynamics code is capable of simulating the solar granulation in detail unequaled by direct observation. We introduce a state-of-the-art numerical tool to the solar physics community and demonstrate its applicability to model the solar granulation. The code is based on the weighted essentially non-oscillatory finite volume method and by its implementation of local mesh...

We derive a first order linear differential equation describing the shape of the probability density function of magnetic field strengths in the quiet Sun (PDF). The modeling is very schematic. It considers convective motions which continuously supply and withdraw magnetic structures. In addition, a magnetic amplification mechanism increases the field strength up to a threshold that cannot be e...

Ca II H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the Ca II H line has not been used as a diagnostic of magnetic flux emergence from the solar interior. Here we report on Hinode observations of chromospheric Ca II H brightenings associated with a repeated, small-scale flux em...

As the result of an eruption, or some other cause tending to produce rapid convection, a gaseous column moves upward from within the sun toward the surface of the photosphere. Vortex motion is initiated by differences in velocity of adjoining surfaces or by irregularities of structure and is maintained by convection. The circulation in the vortex is vertically upward and then outward along the ...

We study the acoustic properties of the solar chromosphere in the high-frequency regime using a time sequence of velocity measurements in the chromospheric Ca II 854.2 nm line taken with the Interferometric Bidimensional Spectrometer (IBIS). We concentrate on quiet-Sun behavior, apply Fourier analysis, and characterize the observations in terms of the probability density functions (PDFs) of vel...