Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations

Details Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations

Oct 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999esasp.446..721z&link_type=abstract

8th SOHO Workshop: Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona. Proceedings of the Conference hel

Other

1

Scientific paper

Observations of the OVI doublet lines at 1032 and 1037 Angstrom have been acquired by UVCS, in August 1996, in the range of heliocentric distances between 1.5 and 2 solar radii, and over a range of latitudes including a 90 degree sector, spanning from equatorial to coronal hole regions. OVI and Lyman alpha line profiles have been discussed in a previous paper (Zangrilli et al., 1999), which focussed on the latitudinal behavior of Hydrogen and Oxygen kinetic temperatures, as a diagnostics of coronal heating processes. In the present paper, emphasis is shifted to the latitudinal behavior of plasma acceleration processes. Information on this issue can be derived via the analysis of the ratio between the intensity of the OVI doublet lines, whose value depends on the outflow speed of Oxygen ions. In order to derive accurate values of the OVI line intensities, we carefully considered the effects of different choices of the background continuum, which turn out to lead to radically different results. The effect of the stray light correction on the intensity ratio of the OVI doublet lines has also been analysed. We discuss our results addressing two issues in particular: i) is there a level, within the range covered by our data, where the wind plasma gets most of its acceleration? ii) does coronal plasma change from a stationary state in streamers to a constant high speed in coronal holes, or is there a well defined latitude where the wind plasma attains a speed maximum? In order to answer these questions we need also to know other coronal parameters, such as densities and expansion factors of the flux tubes. Densities have been derived on the basis of a technique which uses the collisional components of Oxygen lines - easily derived from total intensities - under the assumption that the electron density dependence on altitude can be expressed in terms of a power law. The expansion factor of coronal flux tubes is not well known; hence, we kept this as a free parameter, and different flux tube geometries have been considered. Results from this work are compared with the latitudinal behavior of the wind speed obtained from other experiments (SWAN, Ulysses).

Affiliated with

Also associated with

No associations

Rating

Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations 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 Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Latitudinal Dependence Of The Outflow Speed Of the Solar Wind From Uvcs Observations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1084987