ILWS Conference, October 5, 2009 Extension of Magnetic Clouds in the Inner Heliosphere as observed from Multi- Spacecraft Aline de Lucas Alisson Dal Lago Rainer Schwenn Alicia L. Clúa de Gonzalez

ILWS Conference, October 5, 2009 Motivation The main motivation of the possibility to observe magnetic clouds at multi-spacecraft and estimate their longitudinal extent in the inner heliosphere.

ILWS Conference, October 5, 2009 The orbits of the Helios 1&2 solar probes in 1976 The mission lasted from Dec to March 1986 The Helios 1&2 solar probe mission Helios had a complete set of particle and field instruments, no optical telescopes

ILWS Conference, October 5, 2009 Helios 1&2 a stereo-mission!

ILWS Conference, October 5, 2009 He 1 He 2 77:28, He 2 77:29, He 1 Helios orbits in 1977 A transient MC driven shock, seen from Helios 1& apart in longitude

ILWS Conference, October 5, 2009 MC seen from Helios 1& apart in longitude shock MC Shocks and MCs were detected by H1,2 and at the Earth HSS

ILWS Conference, October 5, 2009 Observation near Earth H2 and IMP-8 are separated by only 9 degrees and they observed similar features. Shocks and MCs were detected by H1,2 and at the Earth HSS shock MC

ILWS Conference, October 5, 2009 MVA for the MC seen by H1,2 and IMP-8 Bx* By* H1 H2 IMP-8 Despite of the different rotations patterns, the direction is the same. Ambiguity of 180º

ILWS Conference, October 5, 2009 Small Separation and Different Magnetic Features

ILWS Conference, October 5, 2009 MVA for the MCs observed by H1 and H2 on DOY 75-76/1977 H1 H2 H1 and H2 are separated by less than 19º. Despite of this fact, the magnetic field rotation inside the MC is different By* Bx*

ILWS Conference, October 5, 2009 H2 and IMP-8 observation H2 is 7º away from the Sun-Earth line. 2 days later

ILWS Conference, October 5, 2009 MVA technique applied to the MC H2 IMP-8 H2 and IMP-8 have the same rotation direction. Clouds’ axes have different orientations. Bx* By*

ILWS Conference, October 5, 2009 Statistics of all „safe“ MCs involving Helios1 & Helios2, IMP8 and ISEE3 Multi-Spacecraft Observed MCs MCs may extend to 90 0 ;

ILWS Conference, October 5, 2009 Shocks extend to larger distances compared to their drivers De Lucas (2009)

ILWS Conference, October 5, 2009 Concluding Remarks MCs showed to behave as well organized structures when analyzed separately by the MVA technique; Some MCs showed different rotation and axial directions according to the measurements from different probes; Could it be that the technique is not accurate enough to analyze this type of structures in order to provide information about their shapes? Or could be that MCs are not completely connected like a long flux tube? MCs observed by Helios extended to smaller distances compared to the shock waves driven by ICMEs.

ILWS Conference, October 5, 2009 THANKS!

ILWS Conference, October 5, 2009

Minimum Variance Analysis (MVA) MVA can tell us the direction of the rotation and the clouds’ orientation. Source: Adapted from Goldstein (1993).