Abstract Details
| Name: Suruchi Goel Affiliation: Physical Research Laboratory Conference ID: ASI2016_810 Title : The statistical study of global properties of sunspots in SoHO/MDI continuum images over solar cycle 23. Authors and Co-Authors : Sami K. Solanki (MPS, Germany), Natalie A. Krivova (MPS, Germany), Shibu K. Mathew (USO, PRL, India) Abstract Type : Oral Abstract Category : Sun and the Solar System Abstract : A better understanding of inter-dependency of various sunspot parameters such as magnetic field, intensity, temperature, size etc., and also their variation with strength of solar activity cycle is important to understand the magneto-convection process involved in sunspot formation and evolution and hence useful to develop a consistent sunspot model. We have investigated global sunspot properties using parameters of sunspots identified from stray-light-corrected continuum images from SoHO/MDI spanning from years 1996 to 2011. We find that the non-linear relation between umbral core intensity and sunspot size is best represented by an exponential function. This non-linear relation shows that the umbrae of large sunspots are relatively darker and cooler than small spots, however it reaches an asymptotic value at 600MSH. For the first time we have also observed that the core intensity depends on shape of umbrae, i.e., circular umbrae are darker compared to the elongated ones. The core intensity also shows small variation with limb position; it increases slightly towards the limb. From our sunspots sampled from complete solar cycle 23 and the rising phase of cycle 24, we did not find any solar-cycle variation in umbral core intensity. Similar to the core intensity the umbral mean intensity decreases with the sunspot size, their relation is well represented by a quadratic function. The penumbra to umbra area ratio has slight dependence on the sunspot area; larger sunspots have relatively higher ratios. Leading and following sunspots usually have different morphological features, however in this study we did not observe significant differences in their core intensity and penumbra-umbra area ratio relation with sunspot area. |