Penumbral-like Filaments in the Solar Photosphere as a Manifestation of Flux Emergence
Abstract
Rare observations of the solar photosphere show the appearance of orphan penumbrae, filamentary structures very similar to a bundle of sunspot penumbral filaments not connected to any umbra. Lim et al. found an orphan penumbra in active region NOAA 11391 near a mature sunspot. We analyze a different data set to study the same structure using the Solar Optical Telescope on board the Hinode satellite. Spectropolarimetric measurements along the Fe I 630.2 nm pair, complemented by G-band and Ca II H filtergrams, show the evolution of this penumbral-like structure and reveal that an emerging flux region is its ancestor. We find new evidence for the interaction between the emerging flux and the pre-existing field that leads to a brightening observed near the base of the chromosphere. Our analysis suggests that as a result of the combination of photospheric flux emergence and magneto-convection in inclined fields the horizontal component of the emerging field can be trapped in the photosphere by the overlying fields and form a structure resembling penumbral filaments.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2014
- DOI:
- 10.1088/2041-8205/786/2/L22
- Bibcode:
- 2014ApJ...786L..22G
- Keywords:
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- Sun: magnetic fields;
- Sun: photosphere;
- sunspots;
- techniques: high angular resolution;
- techniques: polarimetric