The influence of fluctuations of the solar emission line profile on the Doppler shift of interplanetary HLy alpha lines observed by the Hubble-Space-Telescope
H. Scherer et al., The influence of fluctuations of the solar emission line profile on the Doppler shift of interplanetary HLy alpha lines observed by the Hubble-Space-Telescope, ASTRO SP SC, 274(1-2), 2000, pp. 133-141
In an earlier research the employment of a radiation transport model with a
ngle-dependent partial frequency redistribution, self-absorption by interpl
anetary hydrogen, realistic solar H-Ly alpha emission profile, and a time d
ependent 'hot' hydrogen model to analyze 5 interplanetary H-Ly alpha glow s
pectra obtained with the Hubble-Space-Telescope-GHRS spectrometer, has not
resulted in unequivocal determination of a set of thermodynamical parameter
s of the interstellar hydrogen The residual discrepancies between the model
and the data concern the observations performed within an interval of 1 ye
ar close to the solar minimum from very similar lines of sight. In this pap
er we investigate by calculating interplanetary H-Ly alpha lines with the u
se of a one hydrogen distribution and several solar H-Ly alpha line profile
s whether this residual may be caused by possible variations in time of the
shape of the solar H-Ly alpha emission line profile which cause variable i
lluminations of the interplanetary gas. These variations of illuminations c
ause variations in Doppler shift of the resonant interplanetary H-Ly alpha
line that can amount to similar or equal to 4 km s(-1) in the line peak. Co
nsequently we conclude that without adequate knowledge of the solar H-Ly al
pha emission line profile during spectral observations of the interplanetar
y hydrogen gas it is impossible to obtain an agreement between models and o
bservations better than by this value.