Abstract Details
| Name: Rahul Yadav Affiliation: Udaipur Solar Observatory/PRL Conference ID: ASI2016_595 Title : The relation between Umbral Dots and phase of Sunspot Authors and Co-Authors : Shibu K Mathew (Udaipur Solar Observatory/PRL) Abstract Type : Poster Abstract Category : Sun and the Solar System Abstract : Understanding the stability and decay of the sunspots is a major problem in modern solar physics. The properties of umbral dots (UDs), which are important part of the sunspot structure, play a crucial role in this direction. UDs are dot-like bright features observed in almost all sunspot umbrae and pores. Based on their location, UDs are classified as peripheral umbral dots (PUDs) and central umbral dots (CUDs). They are thought to be manifestations of magnetoconvection in sunspot umbrae. Objective of this work is to determine if there is a relationship between UDs properties and phase of sunspot. We employ high-resolution G-band filtergrams observed for six regular isolated sunspots from the Solar Optical Telescope (SOT) on board Hinode at the spatial resolution of 0.0541 arcsec/pixel. We examine the decay rate and phase of sunspots from SoHO/MDI 6-hrs full disk continuum images. The MDI continuum images are first corrected for the limb-darkening, stray-light and then flat-fielded prior to determine the decay rates of sunspots. We apply an image segmentation method and object tracking algorithm on a series of the G-band filtergrams in order to analyse the UD properties. It is found that the decay rates of sunspots vary from 0.023 to 0.06 million km 2 /hr and the effective diameter value of CUDs and PUDs is 0.22 (0.042) arcsec and 0.33 (0.04) arcsec, respectively. Further we observe that there is no clear correlation between decay rate and effective diameter of UDs. However, we notice correlation between the decay rate and UDs density. |