Magnetic field draping and pile up boundary at Comet Halley from Vega-1 observations

DELVA, M.; BERTUCCI, C.; MAZELLE, C.; SCHWINGENSCHUH, K.

Congreso; 35th COSPAR Scientific Assembly; 2004

The start of the Rosetta mission to Comet Churyumov-Gerasimenko and new insights in the plasma regions of non-magnetic solar system bodies lead to re-investigation of magnetic field data from the Vega-1 mission to Comet Halley (1986). Recently, the magnetic pile up boundary has been identified as a common feature for all atmospheric unmagnetized bodies. This boundary marks the outer edge of the magnetic pile up region, known as the magnetic barrier region, where the magnetic field is strong and highly draped. From the Vega-1 magnetometer data, the magnetic field draping around Comet Halley was initially clearly identified through reversal of the field component in direction to the Sun at closest approach. In addition, a more detailed analysis is now performed in regions further upstream in the magnetosheath. The Vega-1 high resolution magnetometer data (10 vectors/sec) on the in-and out-bound leg but inside the bow wave are reinvestigated in search for the magnetic pile up boundary as an indicator for the outer edge of the magnetic barrier. The magnetic field pile up region with enhancement of field draping is studied by means of correlation-techniques, which proved very successful for Venus, Mars and also for comets Giacobini-Zinner and Halley in the case of Giotto observations. Furthermore, this promising technique is also relevant for the upcoming mission Venus-Express, carrying two magnetometers, and is expected to reveal further details about the nature of the magnetic barrier at Venus.