The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-Driven Shock

Author: Gopalswamy, Nat
Published: June 29, 2011.
Physical Description: 1 electronic document
Additional Creators: Yashiro, Seiji

Online Version

hdl.handle.net , Connect to this object online.

Availability

Finding items...

Restrictions on Access

Unclassified, Unlimited, Publicly available.
Free-to-read Unrestricted online access

Summary

We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfven Mach number, and hence the Alfven speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from approximately 48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

Other Subject(s)

Solar Physics

Collection

NASA Technical Reports Server (NTRS) Collection.

Note

Document ID: 20150007924.
GSFC-E-DAA-TN22240.
The Astrophysical Journal; Volume 736; No. 1; L17.

Terms of Use and Reproduction

View MARC record | catkey: 15414016