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An observational study of a magneto-acoustic wave in the solar corona
Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H. +5 more
The Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-s oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode magneto-acoustic wave that travels through the loop apex with a velocity of 2100 km s-1. We u…
The OIV and SIV intercombination lines in the ultraviolet spectra of astrophysical sources
Doyle, J. G.; Madjarska, M. S.; Mathioudakis, M. +8 more
New electron density diagnostic line ratios are presented for the OIV 2s22p 2P-2s2p24P and SIV 3s23p 2P-3s3p24P intercombination lines around 1400Å. A comparison of these with observational data for the symbiotic star RR Telescopii (RR Tel), obtained with the Space Telescope Imaging…
Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation - I. Non-thermal transport of helium ions
Jordan, C.; Smith, G. R.
Models of the solar transition region made from lines other than those of helium cannot account for the strength of the helium lines. However, the collisional excitation rates of the helium resonance lines are unusually sensitive to the energy of the exciting electrons. Non-thermal motions in the transition region could drive slowly ionizing heliu…
Bulk flow velocities in the solar corona at solar maximum
Simnett, G. M.; Lewis, D. J.
We present velocity estimates of bulk motions seen in the solar corona by the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. These estimates reflect the mass-weighted mean outflow of all coronal mass ejections (CMEs) seen during a 1-yr period on the approach to solar maximum. The par…
Relationship between horizontal flow velocity and cell size for supergranulation using SOHO Dopplergrams
Singh, Jagdev; Paniveni, U.; Krishan, V. +1 more
A study of 90 supergranular cells obtained from SOHO Dopplergrams was undertaken in order to investigate a possible relation between the sizes and peak horizontal velocities of the cells. For the sample obtained, the two parameters are found to be correlated with a relation: horizontal velocity ~(size)1/3. This is in agreement with the …