English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The effect of the electron density stratification on the intensity profilesof the H I Ly-$\alpha$ line and the O VI and Mg X doublets formed in solarcoronal holes is investigated. We employ an analytical 2-D model of the largescale coronal magnetic field that provides a good representation of the coronaat the minimum of solar activity. We use the mass-flux conservation equation todetermine the outflow speed of the solar wind at any location in the solarcorona and take into account the integration along the line of sight (LOS). Themain assumption we make is that no anisotropy in the kinetic temperature of thecoronal species is considered. We find that at distances greater than 1 Rsunfrom the solar surface the widths of the emitted lines of O VI and Mg X aresensitive to the details of the adopted electron density stratification.However, Ly-$\alpha$, which is a pure radiative line, is hardly affected. Thecalculated total intensities of Ly-$\alpha$ and the O VI doublet depend to alesser degree on the density stratification and are comparable to the observedones for most of the considered density models. The widths of the observedprofiles of Ly-$\alpha$ and Mg X are well reproduced by most of the consideredelectron density stratifications, while for the O VI doublet only fewstratifications give satisfying results. The densities deduced from SOHO dataresult in O VI profiles whose widths and intensity ratio are relatively closeto the values observed by UVCS although only isotropic velocity distributionsare employed. These density profiles also reproduce the other consideredobservables with good accuracy. Thus the need for a strong anisotropy of thevelocity distribution (i.e. a temperature anisotropy) is not so clear cut asprevious investigations of UVCS data suggested. ...

Sensitivity of solar off-limb line profiles to electron density stratification and the velocity distribution anisotropy