Authors: Kucharek, H, F.M. Ipavich, R. Kallenbach, B. Klecker, H.
Grünwaldt, M. R. Aellig, P.
Bochsler
Reference: IAU General Assembly, Manchester, August 2000
Abstract:
Solar matter is a geochemical reference for the original composition
of the protosolar nebula from which the solar system formed. Therefore,
the Sun represents the least biased sample of interstellar matter and the
solar wind provides the most
comprehensive source of information about solar isotopic abundance. From in
situ measurements of the
solar wind one obtains informations on the present-day isotopic composition
of the outer convective zone of the Sun. The flow dynamic of the solar wind
is determined by the
magnetic topology of the flux tubes and is different for slow and fast
solar wind, respectively. The
slow solar wind originates from closed field line regions whereas the high
speed solar wind is emitted
from open flux tubes in coronal holes. Data from the Mass Time-of-Flight
spectrometers MTOF and CTOF
on board SOHO have been accumulated for time periods in which coronal hole
and non-coronal hole type
plasma has been detected by using different methods in order to determine
the abundance ratios of
magnesium isotopes in these two
different source regions of the solar wind. The results as well as limits
will be discussed in the
context of existing theories.