![]() ![]() Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We question the “fallen magnetic flux tubes” penumbra formation scenario and favor a scenario in which inclined fields emerge from below the surface and are blocked by the overlying chromospheric canopy. However, our results demonstrate that inclined fields in the chromospheric canopy are not needed for the development of inclined fields in the photosphere. This indicates that a chromospheric canopy is a necessary condition for the formation of a penumbra. The existence of a penumbra is found to be determined by the conditions in the chromosphere. Additionally, thin filamentary structures with a maximum width of 0.1″ are seen in photospheric high-resolution TiO-band images in this region.Ĭonclusions. In the region showing no penumbra, almost vertical chromospheric magnetic fields are observed. However, in higher layers the magnetic properties are different. In the deepest atmospheric layers, we find that the magnetic properties (inclination and field strength distribution) measured on the sunspot sector with fully-fledged penumbra are similar to those measured on the sector without penumbra. Additionally, imaging data from the BBI instrument, attached to the GREGOR telescope, in TiO-band and G-band were analyzed. We compared the photospheric and chromospheric magnetic topology of a sunspot sector with a fully-fledged penumbra to a sector where no penumbra formed. Atmospheric parameters were obtained from the deep photospheric Ca I 10 839 Å line (VFISV inversion code), the mostly photospheric Si I 10 827 Å line (SIR inversion code), and the chromospheric He I 10 830 Å triplet (HAZEL inversion code). Spectropolarimetric observations of NOAA AR 12776 from the GRIS spectrograph at the GREGOR telescope were analyzed. Another aim is to find the origin of the inclined magnetic fields. We investigate the existence of a chromospheric canopy as a necessary condition for the formation of a penumbra. While it is conjectured that a chromospheric canopy plays a role in penumbra formation, it has been difficult to find observational evidence of the connectivity between the photosphere and the chromosphere.Īims. University of Geneva, 7 route de Drize, 1227 Carouge, SwitzerlandĪstronomical Institute, University of Bern, SidlerstraBern, SwitzerlandĬontext. 6, 79104 Freiburg, GermanyĮ-mail: de Astrofísica de Canarias (IAC), Vía Láctea s/n, 38205 La Laguna, Tenerife, Spainĭepartamento de Astrofísica, Universidad de La Laguna, Avenida Astrofísico Francisco Sánchez, s/n, 38205 La Laguna, Tenerife, SpainĪstronomical Institute, Slovak Academy of Sciences, PO Box 18, 05960 Tatranská Lomnica, Slovak Republic Leibniz-Institut für Sonnenphysik (KIS), Schöneckstr. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes ![]()
0 Comments
Leave a Reply. |