The Solar Rotation in the 1930s from the Sunspot and Flocculi Catalogs of the Ebro Observatory
The tables of sunspot and flocculi heliographic positions included in the catalogs published by the Ebro Observatory in the 1930s have recently been recovered and converted into digital format by using optical character recognition (OCR) technology. We here analyzed these data by computing the angul...
| Autores: | , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2016 |
| País: | España |
| Recursos: | Universitat Ramon Llull (URL) |
| Repositório: | DAU Arxiu Digital de la Universitat Ramon Llull |
| OAI Identifier: | oai:dau.url.edu:20.500.14342/5411 |
| Acesso em linha: | http://hdl.handle.net/20.500.14342/5411 https://doi.org/10.1007/s11207-016-0974-2 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Rotation Active regions, velocity field Sunspots, velocity Solar cycle, observations |
| Resumo: | The tables of sunspot and flocculi heliographic positions included in the catalogs published by the Ebro Observatory in the 1930s have recently been recovered and converted into digital format by using optical character recognition (OCR) technology. We here analyzed these data by computing the angular velocity of several sunspot and flocculi groups. A difference was found in the rotational velocity for sunspots and flocculi groups at high latitudes, and we also detected an asymmetry between the northern and southern hemispheres, which is especially marked for the flocculi groups. The results were then fitted with a differential-rotation law [ω= a+ bsin 2B] to compare the data obtained with the results published by other authors. A dependence on the latitude that is consistent with former studies was found. Finally, we studied the possible relationship between the sunspot/flocculi group areas and their corresponding angular velocity. There are strong indications that the rotational velocity of a sunspot/flocculi group is reduced (in relation to the differential rotation law) when its maximum area is larger. |
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