| Title |
| Observational Study of Activities on the Solar Surface |
| Received 2008 Feb 4; accepted 2008 Feb 8 |
| Author(s) |
| Kenichi Otsuji |
| Abstruct |
| In this thesis I present my studies about active phenomena observed on the solar surface. The main subjects of the study are magnetic flux emergence and filament eruption. This thesis consists of three parts. The part one is about an emerging flux region observed at Hida observatory. With a method called "cloud model", I obtained the Doppler velocity map of rising magnetic flux. The evolution of magnetic field strength is also studied. And discussions are given on the effect of preexistent magnetic field on the dynamics of flux emergence. In the part two, I summarize my paper published in 2007 November 30, in PASJ. The paper contains the initial result of Hinode, a highly sophisticated observational satellite. With the highest resolution of solar optical telescope aboard Hinode, I studied the evolution of a small emerging flux region, mainly from the morphological point of view. Discussions are given by referencing to the theoretical simulation works. In the part three, I applied the same method as the part one to a filament eruption observed at Hida observatory. The Doppler velocity of erupting filament is combined with the tangential velocity of the apparent motion to obtain three dimensional velocity distribution. I estimated the mass distribution of the filament to obtain the kinetic energy (rotational and translational energy) of the eruptive filament. I believe that the detailed quantitative estimate of erupting filament energy provide basic data for clearing the driving mechanism of the eruption. |
| Title |
| Small Scale Magnetic Flux Emergence Observed with Hinode/Solar Optical Telescope |
| Received 2007 May 31; accepted 2007 September 18 |
| Author(s) |
| Kenichi Otsuji, Kazunari Shibata, Reizaburo Kitai, Satoru Ueno, Shin'ichi Nagata, Takuma Matsumoto, Tahei Nakamura, Hiroko Watanabe, Saku Tsuneta, Yoshinori Suematsu, Kiyoshi Ichimoto, Toshifumi Shimizu, Yukio Katsukawa, Theodore D. Tarbell, Bruce W. Lites, Richard A. Shine, and Alan M. Title |
| Abstruct |
| We observed small scale magnetic flux emergence in a sunspot moat region by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We analyzed filtergram images observed in the wavelengths of Fe 6302 Å, G-band and Ca II H. In Stokes I images of Fe 6302 Å, emerging magnetic flux were recognized as dark lanes. In G-band, they showed their shapes almost the same as in Stokes I images. These magnetic flux appeared as dark filaments in Ca II H images. Stokes V images of Fe 6302 Å showed pairs of opposite polarities at footpoints of each filament. These magnetic concentrations are identified to correspond to bright points in G-band/Ca II H images. From the analysis of time-sliced diagrams, we derived following properties of emerging flux, which are consistent with the previous works. (1) Two footpoints separate each other at a speed of 4.2 km/s during the initial phase of evolution and decreases to about 1 km/s in 10 minutes later. (2) Ca II H filaments appear almost simultaneously with the formation of dark lanes in Stokes I in the observational cadence of 2 minutes. (3) The lifetime of the dark lanes in Stokes I and G-band is 8 minutes, while that of Ca filament is 12 minutes. An interesting phenomena was observed that an emerging flux tube expands laterally in the photosphere with a speed of 3.8 km/s. Discussion on the horizontal expansion of flux tube will be given with refernce to previous simulation studies. |