Kavli Affiliate: Robert Cameron
| First 5 Authors: Sudip Mandal, Natalie A. Krivova, Robert Cameron, Sami K. Solanki,
| Summary:
Size distribution of sunspots provides key information about the generation
and emergence processes of the solar magnetic field. Previous studies on the
size distribution have primarily focused on either the whole group or
individual spot areas. In this paper, we investigate the organization of spot
areas within sunspot groups. In particular, we analyze the ratio, $rm{R}$, of
the area of the biggest spot ($rm{A_{big_spot}}$) inside a group, to the
total area of that group ($rm{A_{group}}$). We use sunspot observations from
Kislovodsk, Pulkovo and Debrecen observatories, together covering solar cycles
17 to 24. We find that at the time when the group area reaches its maximum, the
single biggest spot in a group typically occupies about 60% of the group area.
For half of all groups, $rm R$ lies in the range between roughly 50% and 70%.
We also find R to change with the group area, $rm{A_{group}}$, such that
$rm{R}$ reaches a maximum of about 0.65 for groups with $rm{A_{group}}approx
200mu$Hem and then remains at about 0.6 for lager groups. Our findings imply a
scale invariant emergence pattern, providing an observational constraint on the
emergence process. Furthermore, extrapolation of our results to larger sunspot
groups may have a bearing on the giant unresolved starspot features found in
Doppler images of highly active sun-like stars. Our results suggest that such
giant features are composed of multiple spots, with the largest spot occupying
roughly 55–75% of the total group area (i.e. of the area of the giant
starspots seen in Doppler images).
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