Authors: Bin Zhuang (University of New Hampshire), Noé Lugaz (University of New Hampshire), Manuela Temmer (University of Graz), Tingyu Gou (Harvard-Smithsonian Center for Astrophysics), Carlos R. Braga (Applied Physics Laboratory, Johns Hopkins University), Nada Al-Haddad (University of New Hampshire)

The three-part structure (bright front, dark cavity, and bright core) of coronal mass ejections (CMEs) in white-light coronagraphic images has been studied for decades. However, with recent advanced observations, the traditional relationship between the observed signatures and the CME substructures has been challenged, e.g., it is under debate whether the bright core consists of the prominence material or magnetic flux rope (MFR) structure, or whether the cavity region is related to the MFR. We study a CME on July 26, 2012, which showed a textbook three-part structure in SOHO/LASCO images associated with an eruptive prominence. This CME can be continuously tracked from the low to high corona by combining observations from SDO/AIA, MLSO/MK4, and LASCO/C2 and C3. The optimal positions of STEREO A and B in 2012 provided additional observations for the CME from different viewpoints. Before the eruption, the prominence was seen to be suspended at the bottom of a dark cavity (related to the MFR structure) in AIA images. We track the kinematic evolution of the CME substructures during the CME eruption. We find that, as for the dark cavity, its evolution was consistent from the low corona at extreme ultra-violet wavelengths to the middle and high corona at white-light wavelengths in terms of morphology and kinematics, which supports that the cavity region was related to the MFR structure. However, the bright core is found to have a complex evolution. Combining kinematic analysis, the appearance of two (fussy and sharp) fronts inside the core region, and the mass increase in the core, we deduce that the bright core region was also related to the (initial) MFR structure but consisted of heated prominence materials, which resulted from magnetic reconnection that occurred after the eruption. We also discuss the location of the bright core relative to the entire CME structure.