The Diagnostic Potential of Transition Region Lines under-going Transient Ionization in Dynamic Events

Дата и время публикации : 2012-04-30T11:25:21Z

Авторы публикации и институты :
J. G. Doyle
A. Giunta
A. Singh
M. S. Madjarska
H. Summers
B. J. Kellett
M. O’Mullane

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 18 pages, 6 figures
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: We discuss the diagnostic potential of high cadence ultraviolet spectral data when transient ionization is considered. For this we use high cadence UV spectra taken during the impulsive phase of a solar flares (observed with instruments on-board the Solar Maximum Mission) which showed excellent correspondence with hard X-ray pulses. The ionization fraction of the transition region ion O V and in particular the contribution function for the O V 1371A line are computed within the Atomic Data and Analysis Structure, which is a collection of fundamental and derived atomic data and codes which manipulate them. Due to transient ionization, the O V 1371A line is enhanced in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature than in ionization equilibrium. The rise time and enhancement factor depend mostly on the electron density. The fractional increase in the O V 1371A emissivity due to transient ionization can reach a factor of 2–4 and can explain the fast response in the line flux of transition regions ions during the impulsive phase of flares solely as a result of transient ionization. This technique can be used to diagnostic the electron temperature and density of solar flares observed with the forth-coming Interface Region Imaging Spectrograph.

Category: Physics