The effect of mass motions inside the coronal loops on emission line profiles

The observed green coronal emission line profiles have been often found to have multi-components. Further examinations reveal that the occurrence of m ulti-components in line profiles is related to the solar cycle variations a s well as the activity of the coronal region. The spatial correspondence be tween the intense loops in active regions and strong multi-components in li ne profiles suggests that the presence of loops affects the line shapes. Th e emission line profiles have been found to be fitted well with single or m ulti-Gaussians with line-of-sight velocities up to 70 km s(-1). A simple ra diative transfer model of coronal emission line profiles is developed which shows that coronal loops with mass motions inside may give rise to multi-c omponents in line profiles. The effects of loop parameters such as electron density, flow velocity and kinetic temperature and the line-of-sight varia tions are studied. It is found that line profiles strongly reflect the phys ical conditions inside the loop.