Magnesium Isotope Abundance in the Solar Wind as Observed with the CELIAS/MTOF-Sensor on Board of the SOHO Spacecraft

H. Kucharek1 , F. M. Ipavich 2 , R. Kallenbach 3 , F. Gliem 4 , H. Grünwald5 ,M. Hilchenbach5, B. Klecker1 , P. Bochsler3 , D. Hovestadt1 and the CELIAS team.

1Max-Planck-Institut f. extraterrestrische Physik, D-85740 Garching, Germany
2Dept. of Physics, University of Maryland, MD 20742, USA
3Physikalisches Institut der Universität Bern, CH-3012 Bern, Switzerland
4Institut für Datenverarbeitung der TU Braunschweig, D-38023 Braunschweig, Germany 5Max-Planck-Institut für Aeronomie, D-37819 Katlenburg-Lindau, Germany

Coronal heating and solar wind acceleration are basically unsolved questions in solar physics. Element and isotope composition measurements in the interplanetary medium can provide important information about the origin of the solar wind. The results of such measurements will give us important informations about the physical processes which transport the neutral atoms from the photosphere of the Sun via the chromosphere to the corona. and how they are ionized and accelerated. The Charge, Element and Isotope Analysis System (CELIAS) [Hovestadt et al., 1995] on the SOHO satellite is desinged to study the composition of the solar wind and of solar energetic particles. It consists of three time-of-flight spectrometers to perform composition measurements. The Mass Time Of Flight spectrometer (MTOF) with its high mass resolution of M/(Delta M)>100 has already measured rare elements and isotopes which have previously not been observeable at all or which have not been resolvable from more abundant neighboring species (see Figure below, left hand side). Using Magnesium isotope data (see Figure below, right hand side), we have studied fractionation effects of solar wind ions on their way from the photosphere to the interplanetary medium.

Hovestadt et al.: CELIAS: The Charge, Element and Isotope Analysis System for SOHO, Solar Phys. 162 (1995) 441