OBSERVED DIFFERENCES BETWEEN LARGE AND SMALL SUNSPOTS

We confirm recent results about the differences in temperature and mag netic field strength between the umbra of large and small sunspots. Fi ve Stokes I- and V-spectra from the darkest cores of three different u mbrae have been analysed with the inversion code of the radiative tran sfer equation by Ruiz Cobo and del Toro Iniesta (1992). The run with d epth of temperature, magnetic field (strength and inclination) and vel ocity along the line of sight are obtained. The larger sunspots turn o ut to be cooler and possesing a larger magnetic field strength, practi cally throughout the whole atmosphere. Neither significant gradients o f the line-of-sight velocity, nor of the magnetic field inclination, a re detected in any of the spots analysed. Two model atmospheres are gi ven corresponding to hot (small) and cool (large) sunspots. The models are, to a large extent, free from effects of penumbral/photospheric s tray-light because it is nearly absent in the large spots and because in the small one, where it is important for the Stokes I-profile, only Stokes V is considered to obtain the model atmosphere. These are the first umbral models in the literature for which a simultaneous determi nation of the magnetic field and thermodynamic stratifications is pres ented. The implications of these stratifications for the energy transp ort in sunspot umbrae are discussed.