Morphological study of penumbral formation
Abstract
Penumbrae are known to be areas of mainly horizontal magnetic field surrounding umbrae of relatively large and mature sunspots. In this paper, we observationally studied the formation of penumbrae in NOAA 10978, where several penumbral formations were observed in G-band images of the Solar Optical Telescope on board Hinode. Thanks to the continuous observation by Hinode, we could morphologically follow the evolution of sunspots and found that there are several paths to the penumbral formation: (1) active accumulation of magnetic flux, (2) rapid emergence of magnetic field, and (3) appearance of twisted or rotating magnetic tubes. In all of these cases, magnetic fields are expected to sustain high inclination at the edges of flux tube concentration longer than the characteristic growth time of downward magnetic pumping.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- December 2014
- DOI:
- 10.1093/pasj/psu084
- arXiv:
- arXiv:1407.4573
- Bibcode:
- 2014PASJ...66S..11K
- Keywords:
-
- convection;
- Sun: magnetic fields;
- Sun: photosphere;
- sunspots;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- accepted for publication in PASJ