Abstract Details
| Name: Sreejith Padinhatteeri Affiliation: Manipal University Conference ID: ASI2017_842 Title : Birth of a Sunspot : What condition trigger formation of a penumbra? Authors and Co-Authors : Sankarasubramanian K., ISRO Satellite Centre. Abstract Type : Poster Abstract Category : Sun and the Solar System Abstract : Formation of penumbra, seen as fibril like structures around a dark magnetic concentration (known as umbra) in the optical band, defines the birth of a sunspot on the solar disk. The exact nature of penumbra formation (like the time and position around the umbra), leading to the birth of a sunspot, is not yet fully understood. Studies of many individual cases of penumbral formation in the past have suggested different critical values for certain parameters (like the total magnetic flux) and conditions as the trigger for penumbral formation. Launch of SDO/HMI has given us opportunity to observe a large number of penumbral forming cases to estimate statistically significant value of these critical parameters and also look into other important parameters for its absence in a statistically significant manner. Results from our study of penumbral formation using last five years of HMI data will be presented. It is clear from this preliminary analysis that parameters like critical flux, area, etc are quite different from earlier far and few estimations. |