On the origin of peculiar active regions
We study the long term evolution of a set of bipolar active regions (ARs) in which the main photospheric polarities are seen to rotate one around the other during several solar rotations. After showing that differential rotation cannot produce this large change in the tilt angle, we interpret this p...
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2002
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03796566_v_n505_p121_Mandrini http://hdl.handle.net/20.500.12110/paper_03796566_v_n505_p121_Mandrini |
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paper:paper_03796566_v_n505_p121_Mandrini2023-06-08T15:40:40Z On the origin of peculiar active regions Active regions Magnetic fields Photosphere Extraterrestrial atmospheres Magnetic fields Magnetic flux Plasmas Rotation Sun Active regions Coriolis force Photospheric polarities Solar rotations Astrophysics We study the long term evolution of a set of bipolar active regions (ARs) in which the main photospheric polarities are seen to rotate one around the other during several solar rotations. After showing that differential rotation cannot produce this large change in the tilt angle, we interpret this peculiar evolution as being the result of the emergence of magnetic flux tubes that are distorted with respect to the classical Ω-loop shape. A possible origin of this distortion is the nonlinear development of a kink-instability. Flux tubes deformed by this mechanism must have the same sign of twist and writhe. From the observed evolution of the tilt of the bipoles, we derive the sign of the writhe of the tube forming each AR; while we compute the sign of the twist from transverse field measurements. Comparing the handedness of the magnetic twist and writhe, we find that the presence of kink-unstable flux tubes is coherent with no more than 32% of the studied cases; so, a small fraction of these peculiar ARs can be explained by this process. Then, we discuss the role that other mechanisms may play inducing the inferred deformation, such as the Coriolis force ort external rotational motions of the plasma as the tube ascends in the convection zone. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03796566_v_n505_p121_Mandrini http://hdl.handle.net/20.500.12110/paper_03796566_v_n505_p121_Mandrini |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Active regions Magnetic fields Photosphere Extraterrestrial atmospheres Magnetic fields Magnetic flux Plasmas Rotation Sun Active regions Coriolis force Photospheric polarities Solar rotations Astrophysics |
| spellingShingle |
Active regions Magnetic fields Photosphere Extraterrestrial atmospheres Magnetic fields Magnetic flux Plasmas Rotation Sun Active regions Coriolis force Photospheric polarities Solar rotations Astrophysics On the origin of peculiar active regions |
| topic_facet |
Active regions Magnetic fields Photosphere Extraterrestrial atmospheres Magnetic fields Magnetic flux Plasmas Rotation Sun Active regions Coriolis force Photospheric polarities Solar rotations Astrophysics |
| description |
We study the long term evolution of a set of bipolar active regions (ARs) in which the main photospheric polarities are seen to rotate one around the other during several solar rotations. After showing that differential rotation cannot produce this large change in the tilt angle, we interpret this peculiar evolution as being the result of the emergence of magnetic flux tubes that are distorted with respect to the classical Ω-loop shape. A possible origin of this distortion is the nonlinear development of a kink-instability. Flux tubes deformed by this mechanism must have the same sign of twist and writhe. From the observed evolution of the tilt of the bipoles, we derive the sign of the writhe of the tube forming each AR; while we compute the sign of the twist from transverse field measurements. Comparing the handedness of the magnetic twist and writhe, we find that the presence of kink-unstable flux tubes is coherent with no more than 32% of the studied cases; so, a small fraction of these peculiar ARs can be explained by this process. Then, we discuss the role that other mechanisms may play inducing the inferred deformation, such as the Coriolis force ort external rotational motions of the plasma as the tube ascends in the convection zone. |
| title |
On the origin of peculiar active regions |
| title_short |
On the origin of peculiar active regions |
| title_full |
On the origin of peculiar active regions |
| title_fullStr |
On the origin of peculiar active regions |
| title_full_unstemmed |
On the origin of peculiar active regions |
| title_sort |
on the origin of peculiar active regions |
| publishDate |
2002 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03796566_v_n505_p121_Mandrini http://hdl.handle.net/20.500.12110/paper_03796566_v_n505_p121_Mandrini |
| _version_ |
1768543755296571392 |