A comparison of theoretical Si VIII emission line ratios with observations from SERTS


Autoria(s): Keenan, Francis; Ramsbottom, Catherine; Katsiyannis, A.C.; Bell, K.L.; Brosius, J.W.; Davila, J.M.; Thomas, R.J.
Data(s)

01/02/2004

Resumo

Recent R-matrix calculations of electron impact excitation rates in N-like Si VIII are used to derive theoretical emission line intensity ratios involving 2s(2)2p(3)-2s2p(4) transitions in the 216 -320 Angstrom wavelength range. A comparison of these with an extensive dataset of solar active region, quiet- Sun, sub-flare and off-limb observations, obtained during rocket flights of the Solar EUV Research Telescope and Spectrograph (SERTS), indicates that the ratio R-1 = I(216.94 Angstrom)/I(319.84 Angstrom) may provide a usable electron density diagnostic for coronal plasmas. The ratio involves two lines of comparable intensity, and varies by a factor of about 5 over the useful density range of 10(8)-10(11) cm(-3). However R-2 = I(276.85 Angstrom)/I(319.84 Angstrom) and R-3 = I(277.05 Angstrom)/I(319.84 Angstrom) show very poor agreement between theory and observation, due to the severe blending of the 276.85 and 277.05 Angstrom lines with Si VII and Mg VII transitions, respectively, making the ratios unsuitable as density diagnostics. The 314.35 Angstrom feature of Si VIII also appears to be blended, with the other species contributing around 20% to the total line flux.

Identificador

http://pure.qub.ac.uk/portal/en/publications/a-comparison-of-theoretical-si-viii-emission-line-ratios-with-observations-from-serts(075ab741-01cd-4dcd-bfc8-42b81ccd8208).html

http://www.scopus.com/inward/record.url?scp=3843079690&partnerID=8YFLogxK

Idioma(s)

eng

Direitos

info:eu-repo/semantics/restrictedAccess

Fonte

Keenan , F , Ramsbottom , C , Katsiyannis , A C , Bell , K L , Brosius , J W , Davila , J M & Thomas , R J 2004 , ' A comparison of theoretical Si VIII emission line ratios with observations from SERTS ' Solar Physics , vol 219 , no. 2 , pp. 251-263 .

Palavras-Chave #/dk/atira/pure/subjectarea/asjc/1900/1912 #Space and Planetary Science #/dk/atira/pure/subjectarea/asjc/3100/3103 #Astronomy and Astrophysics
Tipo

article