N. Mein

Observational characteristics and association of umbral oscillations and running penumbral waves

Context. Umbral flashes (UFs) and running penumbral (RP) waves are believed to be closely related oscillatory phenomena of sunspots. Aims. We investigate the association of UFs and RP waves to see whether the latter are a visual pattern created by a common source with UFs or a trans-sunspot wave driven by UFs. Methods. Simultaneous, two-dimensional, dual-line observations in

Dual-line spectral and phase analysis of sunspot oscillations

ion{Ca}{ii}

Non-LTE diagnostics of velocity fields during the gradual phase of a solar flare

xa08542xa0u2009Au2000and

Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

{rm Halpha}

Non-LTE inversion of chromospheric Caii cloud-like features

6563xa0A, obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph mounted on the German VTT at Teide Observatory on Tenerife, are used for this study. High-cadence 8xa0s Doppler velocity images, spectrograms, and spectral-analysis results are used to study the characteristics and the relationship of UFs and RP waves. Results. Several UFs were observed that seem to fill the whole umbra. Doppler velocity variations with time indicate a shock behaviour for UFs, as well as for umbral and RP waves and a smooth continuous propagation of the latter from the umbra through the umbra-penumbra boundary out to the edge of the penumbra. Furthermore, the spectral analysis shows a decreasing oscillatory frequency as we move from the umbra outwards and a jump at the umbra–penumbra boundary that could possibly reflect, apart from a change in physical conditions, a drastic change of the magnetic field inclination with respect to the vertical. Conclusions. The results do not permit us to convincingly support one scenario over the other (i.e. visual pattern vs. trans-sunspot wave) for RP waves; however, they do provide important constraints for future models of sunspot oscillations and RP waves.

Magnetic flux tubes observed with THEMIS/MSDP

Context. Sunspots exhibit a wide range of oscillatory phenomena within their umbrae and penumbrae. Aims. We investigate the behavior of intensity and Doppler velocity oscillations in the umbra and the penumbra to study sunspot oscillations and their associations. Methods. Simultaneous, high-cadence (8xa0s), two-dimensional,

CLOUD MODEL WITH VARIABLE SOURCE FUNCTION FOR SOLAR HALPHA STRUCTURES

ion{Ca}{ii}

Mechanical flux in the solar chromosphere. II - Determination of the mechanical flux

xa08542xa0u2009Au2000and

CLOUD MODEL WITH VARIABLE SOURCE FUNCTION FOR SOLAR HALPHA STRUCTURES. II. DYNAMICAL MODELS

{rm Halpha}

A NON-LTE INVERSION PROCEDURE FOR CHROMOSPHERIC CLOUD-LIKE FEATURES

6563 Au2000observations are used. Doppler velocity and intensity variations are studied with a wavelet spectral, phase difference and coherence analysis, both at distinct positions and within the whole umbra and the penumbra. Results. The analysis reveals the presence of several umbral flashes (UFs) that seem to fill the whole umbra. The spectral analysis indicates oscillating elements of size 2.5″u2000to 5″u2000within the umbra with periods around the 3-min band and oscillation periods around the 5-min band within the penumbra. Two remarkable jumps of the oscillation period and the intensity-velocity phase difference are present at both umbra-penumbra and penumbra-superpenumbra boundaries reflecting a drastic change in physical and/or magnetic conditions. The intensity-velocity phase analysis shows a delay of the intensity response to the velocity variations in accordance with the physics of the observed sawtooth velocity behavior. Most of the UFs oscillate incoherently, while the calmest umbral area seems to be associated with velocity spreading from neighboring UFs. The derived incoherency among UFs in conjunction with the existence of coherently oscillating elements within the umbra suggests the presence of umbral areas with slightly different physical and/or magnetic field conditions. Conclusions. The presented analysis provides further important constraints for realistic models and theoretical interpretations describing sunspot oscillations.