Sun to 1 AU Propagation of a Slow Streamer-Blowout Coronal Mass Ejection

We present the time history and evolution of the 3-dimensional size, shape, and orientation of the slow, classic streamer blowout CME of 2008 Jun 01 by combining STEREO-A remote imaging of its interplanetary propagation with in situ STEREO-B plasma and field measurements at 1~AU. The STEREO-A HI coverage allows unambigious identification of the CME white light front-cavity structure and the resulting ICME flux rope boundaries in running difference images. The elongation-time tracks predict the arrival of the ICME at STEREO-B on 2008 June 06 remarkably well. Starting from the simplest in situ flux rope model for the coherent magnetic cloud field structure, we utilize the unprecedented coverage of the coronal and heliospheric imaging observations to obtain important corrections for the ICME flux rope geometry. MHD modeling results obtained from the NASA Community Coordinated Modeling Center for the ambient heliopsheric solar wind stream structure and a simple CME-like density-pulse propagation are used to verify the overall propagation direction and characterize some of the observed evolutionary properties. The ICME radial expansion, i.e. the time evolution of the flux rope radius Rc(t) from the STEREO-A elongation-time plots, is well approximated by the standard treatment of constant radial expansion Vexp = 24.5 km/s measured from the in situ bulk velocity profile. The 3-dimensional spatial orientation of the ICME flux rope determined by forward modeling in the inner heliosphere shows excellent agreement with the observed 1~AU flux rope orientation and evidence for large scale rotation of the ICME flux rope during its propagation, as predicted by recent numerical simulations. In addition, measurements of the CME's latitudinal angular width allows us to improve the estimate the actual flux rope cross-sectional area and measurements of the CME's longitudinal extent allows us to estimate a more realistic CME ``loop length". These geometric quantities are used to improve the estimates of the ICME in situ toroidal and poloidal magnetic fluxes, ΦT and ΦP. The in situ flux values are then compared to the magnetic fluxes inferred from this event's source region, which includes a substantial portion of the large scale coronal helmet streamer belt. We conlude by discussing our results in the context of both CME initiation and the physical mechanism(s) that energize the pre-eruption configuration. Support for this work was provided by NASA HGI NNX08AJ04G.