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Small Solar Wind Transients and Their Connection to the Large-Scale Coronal Structure
Luhmann, J. G.; Russell, C. T.; Kilpua, E. K. J. +9 more
It has been realized for some time that the slow solar wind with its embedded heliospheric current sheet often exhibits complex features suggesting at least partially transient origin. In this paper we investigate the structure of the slow solar wind using the observations by the Wind and STEREO spacecraft during two Carrington rotations (2054 and…
The ARTEMIS Catalog of LASCO Coronal Mass Ejections. Automatic Recognition of Transient Events and Marseille Inventory from Synoptic maps
Llebaria, A.; Lamy, P.; Boursier, Y. +2 more
The LASCO-C2 coronagraph aboard the SOHO solar observatory has been providing a continuous flow of coronal images since 1996. Synoptic maps for each Carrington rotation have been built from these images, and offer a global view of the temporal evolution of the solar corona, particularly the occurrence of transient events. Coronal Mass Ejections (C…
Solar - Terrestrial Simulation in the STEREO Era: The 24 - 25 January 2007 Eruptions
Vourlidas, A.; Lugaz, N.; Roussev, I. I. +1 more
The SECCHI instruments aboard the recently launched STEREO spacecraft enable for the first time the continuous tracking of coronal mass ejections (CMEs) from the Sun to 1 AU. We analyze line-of-sight observations of the 24 - 25 January 2007 CMEs and fill the 20-hour gap in SECCHI coverage in 25 January by performing a numerical simulation using a …
Solar Wind Sources in the Late Declining Phase of Cycle 23: Effects of the Weak Solar Polar Field on High Speed Streams
Luhmann, J. G.; Russell, C. T.; Arge, C. N. +6 more
The declining phases of solar cycles are known for their high speed solar wind streams that dominate the geomagnetic responses during this period. Outstanding questions about these streams, which can provide the fastest winds of the solar cycle, concern their solar origins, persistence, and predictability. The declining phase of cycle 23 has laste…
X-Ray Jet Dynamics in a Polar Coronal Hole Region
Golub, Leon; Filippov, Boris; Koutchmy, Serge
New X-ray observations of the north polar region taken from the X-ray Telescope (XRT) of the Hinode spacecraft are used to analyze several time sequences showing small loop brightenings with a long ray above. We focus on the formation of the jet and discuss scenarios to explain the main features of the events: the relationship with the expected su…
Modelling the Longitudinal Asymmetry in Sunspot Emergence: The Role of the Wilson Depression
Watson, F.; Fletcher, L.; Dalla, S. +1 more
The distributions of sunspot longitude at first appearance and at disappearance display an east-west asymmetry that results from a reduction in visibility as one moves from disk centre to the limb. To first order, this is explicable in terms of simple geometrical foreshortening. However, the centre-to-limb visibility variation is much larger than …
3D Temperatures and Densities of the Solar Corona via Multi-Spacecraft EUV Tomography: Analysis of Prominence Cavities
Frazin, Richard A.; Kamalabadi, Farzad; Vásquez, Alberto M.
Three-dimensional (3D) tomographic analysis of extreme ultraviolet (EUV) images is used to place empirical constraints on the corona's temperature and density structure. The input data are images taken by the EUVI instrument on STEREO A and B spacecraft for Carrington Rotation 2069 (16 April to 13 May 2008). While the reconstructions are global, w…
Study of CME Propagation in the Inner Heliosphere: SOHO LASCO, SMEI and STEREO HI Observations of the January 2007 Events
Webb, D. F.; Harrison, R. A.; Odstrcil, D. +8 more
We are investigating the geometric and kinematic characteristics of interplanetary coronal mass ejections (ICMEs) using data obtained by the LASCO coronagraphs, the Solar Mass Ejection Imager (SMEI), and the SECCHI imaging experiments on the STEREO spacecraft. The early evolution of CMEs can be tracked by the LASCO C2 and C3 and SECCHI COR1 and CO…
STEREO/SECCHI Observations on 8 December 2007: Evidence Against the Wave Hypothesis of the EIT Wave Origin
Zhukov, A. N.; Rodriguez, L.; de Patoul, J.
The physical nature of EIT waves, large-scale bright fronts propagating in the solar corona, remains a subject of a continuing debate. Two main ways of interpreting this phenomenon have been suggested. One of them describes an EIT wave as a fast mode magnetosonic wave freely propagating in the corona. The other interpretation does not consider an …
Interpretation of Solar Magnetic Field Strength Observations
Ulrich, R. K.; Bertello, L.; Boyden, J. E. +1 more
This study based on longitudinal Zeeman effect magnetograms and spectral line scans investigates the dependence of solar surface magnetic fields on the spectral line used and the way the line is sampled to estimate the magnetic flux emerging above the solar atmosphere and penetrating to the corona from magnetograms of the Mt. Wilson 150-foot tower…