Observations of a sunspot region located near the center of the solar disk were obtained on October 3, 1994, with the Multichannel Subtractive Double Pass Spectrograph (MSDP). This instrument, operating in Hα, was installed at the focus of the VTT at Tenerife (Canary Islands) and provided Hα intensity profiles at every pixel of the field of view. Reconstruction of the Hα profile allowed the com...

Temporal intensity variations of umbral dots (UDs) and dark nuclei (DNs), and proper motions of UDs, were analyzed in a 4 1/2 hour time series of high resolution white light images of the umbra in a medium-size sunspot (NOAA 7519). The observationsweremade on 5 June 1993 at the SwedishVacuum Solar Telescope, La Palma. An identification and tracking algorithm was applied to UDs observed in a des...

A partial decrease of the convective energy by the magnetic field of a sunspot causes the temperature of the magnetized plasma to decrease and this leads to a magneto-hydrostatic equilibrium. Thus, we expect a strong relation between magnetic field strength of a sunspot and its temperature/brightness. Here, we investigate this relation in the umbra of the large sunspot in NOAA10930 using spectr...