Abstract Details

Name: Tanmoy Samanta
Affiliation: Indian Institute of Astrophysics
Conference ID: ASI2017_651
Title : Fine-structure dynamics in the sunspot penumbra and their coupling through the different solar atmospheric layers
Authors and Co-Authors : Hui Tian: School of Earth and Space Sciences, Peking University, China; Dipankar Banerjee: Indian Institute of Astrophysics, India; Nicole Schanche: Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
Abstract Type : Poster
Abstract Category : Sun and the Solar System
Abstract : Sunspots are regions of concentrated strong magnetic fields and appear dark in the central region known as the umbra. Umbra is generally surrounded by a less darker region called the penumbra. Though the sunspots have been observed over centuries, their fine structures and their counterparts in the higher solar atmosphere have been revealed in recent decades with the advancement of high-resolution and multi-wavelength observations. With the advancement of high-resolution instruments, fine structures and their dynamics are being studied. Penumbral microjets (PMJs) are one of the prominent fine-structure dynamical features observed in the sunspot at the chromospheric height. Furthermore, recent high-resolution observations reveal that subarcsecond bright dots (BDs) with sub-minute lifetimes appears ubiquitously in the transition region (TR) above sunspot penumbra. It was proposed that both the PMJs and BDs are formed due to magnetic reconnection process and may play an important role in heating of the penumbra. It was also proposed that PMJs which originate as a result of magnetic reconnection at lower height may progressively heat up to TR temperature and may appears as BDs. Using simultaneous observation of the chromosphere from the Solar Optical Telescope (SOT) aboard Hinode and the TR from the Interface Region Imaging Spectrograph (IRIS), we study the dynamics of BDs and their relation with PMJs. We find two types of BDs, one which is related to PMJs and the others which do not show any visible dynamics in the SOT Ca II H images. From a statistical analysis we show that these two types have different properties. The BDs which are related to PMJs always appear at the top of the PMJs, show inward motion and originate before the generation of the PMJs. These behavior is puzzling and can not be explain by earlier reconnection model. Our results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere.