Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fractal dimensions of umbral and penumbral regions of sunspots   The images of sunspots in sixteen active regions taken at the UCCI
Observatory in Grand Cayman during June - November 2015, were used to determine
their fractal dimensions using the perimeter-area method for the umbral and the
penumbral region. Scale free fractal dimensions of 2.09 $\pm$ 0.42 and 1.72
$\pm$ 0.4 were found respectively. This value was higher than the value
determined by Chumak and Chumak (1996) who used a similar method but for the
penumbral region only for their sample set. There is a positive correlation r =
0.58 between umbral and the penumbral fractal dimensions for the specific
sunspots. Furthermore, a time series analysis was done similarly on eight
images of AR 12403, from 21st August 2015 - 28th August 2015 taken from the
Debrecen Photoheliographic Data (DPD). The correlation, r = 0.623 between the
umbral and penumbral fractal dimensions in the time series indicating that the
complexity in morphology indicated by the fractal dimension between the umbra
and penumbra followed each other in time as well.

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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int