34th Solar Physics Division Meeting, June 2003
Session 4 Corona II
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[4.08] Electron Temperature and Speed Measurements in the Lower Solar Corona: Results from the June 2001 Eclipse

N.L. Reginald (CUA/GSFC), O.C. St.Cyr, J.M. Davila (NASA/GSFC), J.W. Brosius (CUA/GSFC)

The determination of the radial and latitudinal temperature and solar wind speed profiles of the solar corona is of immense importance in understanding the coronal heating mechanism and the dynamics of the coronal features. Cram (Sol. Phys, 48, 3, 1976) provided the theory for the formation of the K-coronal spectrum and a method for determining the radial profile of the coronal temperature.

We have modified Cram's theory to incorporate the role of the solar wind in the formation of the K-corona and have identified both temperature and speed sensitive intensity ratios. We built MACS (Multi Aperture Coronal Spectrometer); a fiber optic based spectrograph to study the total solar eclipse of June 2001 in Lusaka, Zambia. In this instrument one end of the five fiber-optic tips at the focal plane of the telescope were positioned to see different latitudes at the same radii on the solar corona. The other ends of the fibers were vertically aligned and placed at the primary focus of the collimating lens of the spectrograph.

We have succeeded in isolating the K-corona from the spectral observations made through two different fibers in MACS to match the theoretical K-coronal profiles for different temperatures and wind speeds. Results were obtained at two locations in the solar corona, one within a helmet streamer at the east limb and the second in a streamer cluster in the southwest. Both points were at an altitude of about 0.1-0.2 R\odot above the solar limb. The east limb location at the edge of a helmet streamer and the southwest location yielded electron temperatures of 0.94 ± 0.01 MK and 1.28 ± 0.02 MK and bulk flow speeds of 124.0 ± 48.0 km/sec and 149.0 ± 59.0 km/sec, respectively. This mechanism provides for simultaneous measurement of both the temperature and wind speed in the field of view of an exposed fiber to the corona. We will also present the details of this experiment.

The author(s) of this abstract have provided an email address for comments about the abstract: reginald@stars.gsfc.nasa.gov

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