The Solar Photospheric-to-Coronal Fe abundance from X-ray Fluorescence Lines

Дата и время публикации : 2011-12-23T10:45:56Z

Авторы публикации и институты :
K. J. H. Phillips

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: Accepted for publication by MNRAS
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: The ratio of the Fe abundance in the photosphere to that in coronal flare plasmas is determined by X-ray lines within the complex at 6.7~keV (1.9~AA) emitted during flares. The line complex includes the He-like Fe (fexxv) resonance line $w$ (6.70~keV) and Fe K$alpha$ lines (6.39, 6.40~keV), the latter being primarily formed by the fluorescence of photospheric material by X-rays from the hot flare plasma. The ratio of the Fe K$alpha$ lines to the fexxv $w$ depends on the ratio of the photospheric-to-flare Fe abundance, heliocentric angle $theta$ of the flare, and the temperature $T_e$ of the flaring plasma. Using high-resolution spectra from X-ray spectrometers on the {em P78-1} and {em Solar Maximum Mission} spacecraft, the Fe abundance in flares is estimated to be $1.6pm 0.5$ and $2.0 pm 0.3$ times the photospheric Fe abundance, the {em P78-1} value being preferred as it is more directly determined. This enhancement is consistent with results from X-ray spectra from the {em RHESSI} spacecraft, but is significantly less than a factor 4 as in previous work.

Category: Physics