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LASCO observations of an Earth-directed coronal mass ejection on May 12, 1997
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +5 more
Coronal mass ejections (CMEs) that occur near the center of the solar disk are most likely to impact Earth. Detection of such events as ‘halos’ in white-light coronagraphs has been somewhat controversial in recent years. We present observations from the LASCO coronagraphs on SOHO that provide convincing evidence of the detection of an Earth-direct…
On the relationship between coronal mass ejections and magnetic clouds
Thompson, B. J.; Nitta, N.; Steinberg, J. T. +9 more
We compare the substructures of the 1997 February 07 coronal mass ejection (CME) observed near the Sun with a corresponding event in the interplanetary medium to determine the origin of magnetic clouds (MCs). We find that the eruptive prominence core of the CME observed near the Sun may not directly become a magnetic cloud as suggested by some aut…
Cradle to grave tracking of the January 6-11,1997 Sun-Earth connection event
Thompson, B. J.; Fox, N. J.; Peredo, M.
During the interval January 6-11, 1997, the satellites and ground facilities of the International Solar-Terrestrial Physics (ISTP) “Observatory” tracked a solar eruption from the Sun to the Earth. The resulting Coronal Mass Ejection (CME) took four days to travel through interplanetary space before arriving at Earth, where it caused electromagneti…
Differences in the O7+/O6+ ratio of magnetic cloud and non-cloud coronal mass ejections
Livi, S.; Woch, J.; Schwenn, R. +7 more
On its trajectory to Jupiter and over the poles of the Sun the Ulysses spacecraft has observed a considerable number of Coronal Mass Ejection (CME) transients in slow and in fast solar wind streams. The analysis of the magnetic field topology and the O7+/O6+ charge state ratio of 56 of these events has yielded strong evidence…
The solar origin of the January 1997 coronal mass ejection, magnetic cloud and geomagnetic storm
St. Cyr, O. C.; Webb, D. F.; Gopalswamy, N. +2 more
The magnetic cloud and geomagnetic storm on January 10-11, 1997 were associated with a halo-type Coronal Mass Ejection (CME) observed by the SOHO/LASCO coronagraphs near the sun on January 6. We summarize the solar activity related to this CME and the subsequent storm at Earth. This solar activity was remarkably weak and unimpressive. If the wide …
Type II radio emissions in the frequency range from 1-14 MHz associated with the April 7, 1997 solar event
St. Cyr, O. C.; Thompson, B. J.; Kaiser, M. L. +4 more
We present an analysis of radio emissions associated with the April 7, 1997 solar eruptive event. The event consisted of a filament disappearance, a complex two-phase coronal mass ejection (CME), and a C6.9, 2N flare. At the same time, intermittent type II radio emissions in the frequency range 1-10 MHz, corresponding to an altitude range of 2-15 …
Energetic (∼ 1 to 50 MeV) protons associated with Earth-directed coronal mass ejections
Laitinen, T.; Vainio, R.; Valtonen, E. +7 more
During the period from January through mid-May, 1997, four large Earth-directed CMEs were observed by the Large Angle Spectroscopic Coronograph (LASCO). These CMEs were associated with long-lasting fluxes of >1.6 MeV protons detected by the Energetic and Relativistic Nuclei and Electron instrument (ERNE). However, the magnitudes of energetic pr…
Radial heliospheric magnetic fields detected by Ulysses
Balogh, A.; Jones, G. H.; Forsyth, R. J.
The magnetometer aboard the Ulysses spacecraft has recorded numerous examples of heliospheric magnetic fields orientated in near-radial directions for periods of several hours or more. These fields are unusual, as their existence is contrary to the predictions of classical theories concerning solar wind production and propagation. The magnetic fie…
Evidence for multiple ejecta: April 7-11, 1997, ISTP Sun-Earth connection event
Reiner, M.; Delaboudinière, J. -P.; Bougeret, J. -L. +12 more
Evidence is presented that the enhanced geomagnetic activity, on April 10-11, 1997, was caused by one of two ejecta that left the Sun at ≈ 14 UT on April 7. This ejecta was not directly detected at the Earth. The evidence for this interpretation is based on WIND spacecraft observations in the solar wind (SW). It is consistent with: (i) measured ve…
Elemental composition of the January 6, 1997, CME
Hsieh, K. C.; Wurz, P.; Bochsler, P. +25 more
Using solar wind particle data from the CELIAS/MTOF sensor on the SOHO mission, we studied the abundance of the elements O, Ne, Mg, Si, S, Ca, and Fe for the time period around the January 6, 1997, coronal mass ejection event (CME). In the interstream and coronal hole regions before and after this event we found elemental abundances consistent wit…