Speaker
Egor Illarionov
(Moscow State University)
Description
We obtain the latitude-time distribution of the averaged tilt angle
of solar bipoles. For large bipoles, which are mainly bipolar
sunspot groups, the spatially averaged tilt angle is positive in the
Northern solar hemisphere and negative in the Southern, with
modest variations during course of the solar cycle. We consider
the averaged tilt angle to be a tracer for a crucial element of the
solar dynamo, i.e. the regeneration rate of poloidal large-scale
magnetic field from toroidal. The value of the tilt obtained crudely
corresponds to a regeneration factor corresponding to about
10% of r.m.s. velocity of solar convection. These results develop
findings of Kosovichev and Stenflo (2012) concerning Joy's law,
and agree with the usual expectations of solar dynamo theory.
Quite surprisingly, we find a pronounced deviation from these
properties for smaller bipoles, which are mainly solar ephemeral
regions. They possess tilt angles of approximately the same
absolute value, but of opposite sign compared to that of the
large bipoles. Of course, the tilt data for small bipoles are less
well determined than those for large bipoles; however they
remain robust under various modifications of the data processing.
Primary authors
Andrey Tlatov
(Kislovodsk Mountian Astronomical Station of the Pulkovo Observatory)
Dmitry Sokoloff
(Moscow State University)
Egor Illarionov
(Moscow State University)
Valery Pipin
(Institute for Solar-Terrestrial Physics, Irkutsk)
