Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft

Details Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsh23a1948p&link_type=abstract

American Geophysical Union, Fall Meeting 2011, abstract #SH23A-1948

Astronomy and Astrophysics

Astrophysics

[7513] Solar Physics, Astrophysics, And Astronomy / Coronal Mass Ejections

Scientific paper

Recent work by Gopalswamy and Yashiro (2011) determined the radial coronal magnetic field strength from 6 to 23 solar radii (Rs) by measuring the standoff distance of a CME-driven shock observed in the coronagraphic field of view. We now extend their work to determine radial magnetic field strength in the heliocentric distance range 6 - 100 Rs using data from COR2 and HI 1 instruments onboard the STEREO spacecraft. We apply the Raytrace model (Thernisien 2006, 2009) to measure the shock standoff distance for the April 5, 2008 CME. In addition, we determine the flux rope curvature by fitting a circle to the CME. The ratio of the standoff distance to the radius of curvature is a known function of the shock Mach number and the adiabatic index. Thus we can obtain the shock Mach number, assuming the value of the adiabatic index. The Alfven velocity can then be calculated using the ambient solar wind velocity, shock velocity obtained from the height-time measurements, and the Mach number. Finally, the radial magnetic field trength is computed from the Alfven speed and the density of the ambient medium. We also compare the derived magnetic field strength with the in-situ measurements made by the Helios spacecraft, which measured the magnetic field in the distance range 60 - 215 Rs. We found that the magnetic field strength decreases from 17 mG at 6 Rs to 1 mG at 100 Rs. In addition, the radial profile can be described by a power law.

Affiliated with

Also associated with

No associations

Rating

Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Determination of the heliospheric radial magnetic field from the Standoff Distance of a CME-driven shock Observed by the STEREO spacecraft will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-877782