Abstract:
The proposed COronal Solar Magnetism Observatory (COSMO) Large Coronagraph (LC)
will provide unique observations to study coronal mass ejections (CMEs) with its ability to
diagnose the magnetic field and plasma properties in the solar corona. In this article, we take
a realistic magnetohydrodynamic CME model and synthesize the signals of several coronal
emission lines (CELs) to perform a forward modeling of COSMO LC observations of a
CME. We use the Stokes parameters of the Fe XIII 10747 Å line to diagnose the magnetic
field and plasma properties of the CME flux rope. The results show that COSMO LC can
provide magnetic field measurements of CME progenitors with a high spatial resolution
(pixel size = 2 ). During a CME eruption, the COSMO LC observations may be used to
qualitatively study the evolution of the magnetic field using a lower spatial resolution (pixel
size = 6 ). We then use the synthetic signals of several other CELs to diagnose the physical
conditions in the CME leading front, including the shock. The COSMO LC observations
of the Fe XIII 10798/10747 Å and Ni XV 8026/6703 Å line pairs could provide density
diagnostics of the front. By observing several CELs with different formation temperatures,
the COSMO LC could be used to diagnose the temperature and ionization states in the
front. We suggest that the Fe XIII 10747 Å line should be given the highest priority when
observing CMEs, while observations of the Fe XIII 10798 Å, Fe XIV 5303 Å, and Fe XV
7062 Å lines, and the Ni XV 8026/6703 Å line pair can also provide valuable information
on CMEs.
