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SOLAR WIND DRAG AND THE KINEMATICS OF INTERPLANETARY CORONAL MASS EJECTIONS

Journal Article · · Astrophysical Journal Letters

Coronal mass ejections (CMEs) are large-scale ejections of plasma and magnetic field from the solar corona, which propagate through interplanetary space at velocities of {approx}100-2500 km s{sup -1}. Although plane-of-sky coronagraph measurements have provided some insight into their kinematics near the Sun (<32 R {sub sun}), it is still unclear what forces govern their evolution during both their early acceleration and later propagation. Here, we use the dual perspectives of the STEREO spacecraft to derive the three-dimensional kinematics of CMEs over a range of heliocentric distances ({approx}2-250 R {sub sun}). We find evidence for solar wind (SW) drag forces acting in interplanetary space, with a fast CME decelerated and a slow CME accelerated toward typical SW velocities. We also find that the fast CME showed linear ({delta} = 1) dependence on the velocity difference between the CME and the SW, while the slow CME showed a quadratic ({delta} = 2) dependence. The differing forms of drag for the two CMEs indicate the forces responsible for their acceleration may be different.

OSTI ID:
21452644
Journal Information:
Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 724; ISSN 2041-8205
Country of Publication:
United States
Language:
English