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Sunspot group tilt angles from drawings for cycles 19-24

Published online by Cambridge University Press:  27 November 2018

Emre Işık Open the ORCID record for Emre Işık [Opens in a new window] ,
Seda Işık  and
Bahar B. Kabasakal
Emre Işık
Affiliation:
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077, Göttingen, Germany email: [email protected] Feza Gürsey Center for Physics and Mathematics, Boğaziçi University, Kuleli 34684 Istanbul, Turkey
Seda Işık
Affiliation:
Kandilli Observatory and Earthquake Research Institute, Boğaziçi University, Kuleli 34684 Istanbul, Turkey
Bahar B. Kabasakal
Affiliation:
Feza Gürsey Center for Physics and Mathematics, Boğaziçi University, Kuleli 34684 Istanbul, Turkey
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Abstract

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The tilt angle of a sunspot group is a critical quantity in the surface transport of magnetic flux and the solar dynamo. To contribute long-term databases of the tilt angle, we developed an IDL routine, which allows the user to interactively select and measure sunspot positions and areas on the solar disc. We measured the tilt angles of sunspot groups for solar cycles 19-24 (1954.6-2017.8), using the sunspot drawing database of Kandilli Observatory. The method is similar to that used in the discontinued Mt. Wilson and Kodaikanal databases, with the exception that sunspot groups were identified manually, which has improved the accuracy of the resulting tilt angles. We obtained cycle averages of the tilt angle and compared them with the values from other datasets, keeping the same group selection criteria. We conclude that the previously reported anti-correlation with the cycle strength needs further investigation.

Keywords

Sun: activitySun: photosphere(Sun:) sunspots
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S340: Long-term Datasets for the Understanding of Solar and Stellar Magnetic Cycles , February 2018 , pp. 133 - 136
Copyright
Copyright © International Astronomical Union 2018 

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