Forgács-Dajka, E., Dobos, L. and Ballai, I. orcid.org/0000-0002-3066-7653 (2021) Time-dependent properties of sunspot groups. I. Lifetime and asymmetric evolution. Astronomy and Astrophysics, 653. A50. ISSN 0004-6361
Abstract
Aims. In this paper, we aim to study the time dependence of sunspot group areas in a large sample composed of various databases spanning over 130 years, used state-of-the-art statistical methods.
Methods. For a carefully selected but unbiased sample, we use Bayesian modelling to fit the temporal evolution of the combined umbral and penumbral area of spot groups with a skew-normal function to determine the existence of any asymmetry in spot growth or decay. Our primary selection criteria guaranteed that only spot groups with a well-defined maximum area were taken into account. We also analysed the covariance of the resulting model parameters and their correlations with the physical parameters of the sunspots and the ongoing solar cycle.
Results. Our results show that the temporal evolution of well-observed sunspot groups that reach at least 50 millionths of a solar hemisphere at their maximum can be fitted surprisingly well with our model. Furthermore, we show significant asymmetry – described by a skew parameter of fitted curves – between the growing and decaying phases of analysed sunspot groups. In addition, we found a weak correlation between the values of skew parameters and the maximum area of sunspot groups and their hemispherical latitude.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 ESO 2021. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | methods: data analysis; methods: statistical; sunspots |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Jun 2021 12:51 |
Last Modified: | 07 Sep 2021 09:50 |
Status: | Published |
Publisher: | EDP Sciences |
Refereed: | Yes |
Identification Number: | 10.1051/0004-6361/202140731 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:175270 |