Iron Isotopes in the Solar Wind: Measurements From SoHO/CELIAS/MTOF

F.M. Ipavich, J.A. Paquette, P. Bochsler, R. Kallenbach, P.Wurz, H. Grünwaldt, M. Hilchenbach, D. Hovestadt

Paper presented at AGU Spring Meeting, 26-29 May 1998, Boston, MA, USA

The MTOF sensor uses time of flight measurements in a harmonic potential region to identify elements and isotopes in the solar wind with excellent mass resolution. MTOF also uses a unique entrance electrostatic deflection system that has a very wide dynamic range (about a factor of 5 in energy per charge); the solar wind mass per charge range is usually covered in just a few steps of the deflection system. The 3-axis stabilized SoHO spacecraft allows MTOF to always sample the solar wind. The combination of mass resolution and collection power resulting from the above makes MTOF ideally suited for making measurements of rare solar wind elements and isotopes.

We present measurements of the Fe54/Fe56 isotope ratio in different types of solar wind flows (as identified from the CELIAS/MTOF Proton Monitor), including samples from low-speed solar wind, CMEs and coronal hole associated flows. Other solar wind characteristics are also summarized for these events. Under many conditions the Fe54/Fe56 isotope ratio can be calculated with a temporal resolution on the order of hours. Our results to date indicate that the iron isotope ratio does not significantly vary in the solar wind, and its value is close to that observed in meteorites.

Return to the CELIAS publication page
Return to the CELIAS home page

Last Update: February 27, 1998, Peter Wurz