Umbral Fine Structures in Sunspots Observed with Hinode Solar Optical Telescope

R. Kitai , H. Watanabe (1) , T. Nakamura (2, 3, 4, 5, 6) , K. Otsuji , T. Matsumoto (7, 8, 9, 10, 11) , S. Ueno , S. Nagata (12) , K. Shibata , R. Muller (13) , K. Ichimoto , S. Tsuneta , Y. Suematsu , Y. Katsukawa , T. Shimizu (14, 15) , T. D. Tarbell , R. A. Shine (16, 17, 18, 19, 20, 21) , A. M. Title , B. Lites

1 ICR - Institute for Chemical Research
2 Institute of Laser Engineering (ILE)
3 NAGOYA LABORATORIES - Pfizer Japan Incorporated
4 Department of Physics [Tokyo]
5 Graduate School of Information Sciences [Sendai]
6 Graduate School of Information Sciences
7 CASSIOPEE - Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides
8 Department of Physics
9 Department of Electrical Engineering and Bioscience
10 Department of Mechanical Engineering and Materials Science
11 NIMS - National Institute for Materials Science
12 Fujitsu Laboratories LTD.
13 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
14 Institut of Multidisciplinary Research for Advanced Materials
15 Fujitsu Laboratories of America, Inc., Sunnyvale
16 Scool of Biological Sciences
17 University of Sydney - Scool of Biological Sciences
18 Biological Sciences A08
19 US - University of Sydney
20 University of Sydney - Biological Sciences
21 Scool of Biological Sciences A08

High resolution imaging observation of a sunspot umbra was done with Hinode Solar Optical Telescope (SOT). Filtergrams in wavelengths of blue and green continuum were taken during three consecutive days. The umbra consisted of a dark core region, several diffuse components and numerous umbral dots. We derived basic properties of umbral dots (UDs), especially their temperatures, lifetimes, proper motions, spatial distribution and morphological evolution. Brightness of UDs is confirmed to depend on the brightness of their surrounding background. Several UDs show fission and fusion. Thanks to the stable condition of space observation, we could first follow the temporal behavior of these events. The derived properties of internal structure of the umbra are discussed in viewpoint of magnetoconvection in a strong magnetic field.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]

R. Kitai, H. Watanabe, T. Nakamura, K. Otsuji, T. Matsumoto, et al.. Umbral Fine Structures in Sunspots Observed with Hinode Solar Optical Telescope. Publications of the Astronomical Society of Japan, 2007, 59, pp.585-591. ⟨hal-00286916⟩