The Large Angle Spectroscopic Coronagraph (LASCO)

Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.; Michels, D. J.; Socker, D. G.; Lamy, Philippe; Llebaria, A.; Maucherat, J.; Schwenn, R.; Bedford, G. M. Simmett hand D. K.; Eyles, C. J.

doi:10.1007/bf00733434

Cited by 2,565 publications

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“…In the following text we report the physical parameters and their radial variations in a narrow, mid-latitude streamer structure, derived from observations carried out through a week in May 2004, during the declining phase of the solar activity cycle 23. The empirical model describing the streamer characteristics presented in this paper is based on analysis of ultraviolet spectroscopic measurements in the extended corona obtained by UVCS and of white-light polarized brightness measurements from the LASCO (Large Angle Spectroscopic COronagraph) C2 coronagraph (Brueckner et al 1995), both aboard the SOHO satellite. The values of these parameters are compared with the properties of streamers observed by SOHO instruments during the course of the solar cycle and/or at latitudes closer to the solar equator, with the aim of contributing to the ongoing campaign devoted to the study of the physical characteristics of coronal streamers (see, e.g., Uzzo et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Spadaro

Susino

Ventura

et al. 2007

A&A

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Context. Investigating the physical properties of solar coronal streamers is important for understanding their role in the global magnetic structure of the extended solar atmosphere, as well as in the generation of the slow solar wind. Aims. We hope to contribute as completely as possible to the ongoing SOHO instruments campaign devoted to the study of the physical characteristics of coronal streamers at various heliocentric distances. Results. Electron densities and temperatures, H i and O vi kinetic temperatures, and outflow velocities were derived from the line intensities and widths, as well as from the O vi line intensity ratio in the 1.6−5 R range of heights, limited to the central region of the streamer. To our knowledge, the H i outflow velocities obtained in this work are the first ones determined inside a streamer structure. They are significantly lower than those of the O vi ions. This, together with the O vi kinetic temperatures that are much higher than the H i ones, suggest that the absorption of Alfvén waves at the ion cyclotron frequency might also occur inside streamers. Methods. We analyzed ultraviolet H iConclusions. In comparison with other streamers described in the literature, the structure examined in this work generally exhibits lower electron density and neutral hydrogen kinetic temperature. Conversely, the O vi kinetic temperature and outflow velocity radial profiles are consistent with the results for the other examined streamers.

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Section: Introductionmentioning

confidence: 99%

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Spadaro

Susino

Ventura

et al. 2007

A&A

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“…More than a 100 years later, a different category of highly energetic transient events on the Sun was discovered (Brückner 1974;Gosling et al 1974), in the course of which huge amounts of gas are violently ejected from the Sun into interplanetary space. Such transients originate from the coronal region of the Sun and are commonly referred as coronal mass ejections (CMEs).…”

Section: Coronal Mass Ejections (Cmes)mentioning

confidence: 99%

“…Associated activities on the solar disk in the form of post-eruptive loops, disappearing filaments (erupting prominences) or flare signatures have been observed (Tripathi et al 2004). The ICME corresponding to a front-side halo CME detected in the field view of SOHO/ LASCO placed on the Sun-Earth line may take a few days to reach the magnetosphere of the Earth (Brückner et al 1995). However, not every halo CME will reach the Earth.…”

Section: Interplanetary Spacementioning

confidence: 99%

“…Radiation effects depend on the energy of the radiation, from galactic cosmic rays, solar energetic particles and radiation trapped in the Earth's Van Allen belts (Bourrieau et al 1996;Crosby et al 2006). A number of spacecraft anomalies and failures following significantly enhanced fluxes of high energy radiation during interplanetary disturbances have been identified (Baker et al 1996, Reeves et al 1998Barbieri and Mahmot 2004 and references therein).…”

Section: Effects On Satellitesmentioning

confidence: 99%

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Space Weather: Physics, Effects and Predictability

2010

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The time varying conditions in the near-Earth space environment that may affect space-borne or ground-based technological systems and may endanger human health or life are referred to as space weather. Space weather effects arise from the dynamic and highly variable conditions in the geospace environment starting from explosive events on the Sun (solar flares), Coronal Mass Ejections near the Sun in the interplanetary medium, and various energetic effects in the magnetosphere-ionosphere-atmosphere system. As the utilization of space has become part of our everyday lives, and as our lives have become increasingly dependent on technological systems vulnerable to the space weather influences, the understanding and prediction of hazards posed by these active solar events have grown in importance. In this paper, we review the processes of the Sun-Earth interactions, the dynamic conditions within the magnetosphere, and the predictability of space weather effects on radio waves, satellites and ground-based technological systems today.

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“…In this work we shall study the solar and interplanetary causes of the 9 great geomagnetic storms observed from January 1997 to April 2001. We use observations made by the Large Angle and Spectroscopic Coronagraph (LASCO), and by the Extreme Ultraviolet Imaging Telescope (EIT), both on board of the Solar and Heliospheric Observatory (SOHO), able to image the solar corona in white light from 2 to 32 solar radii [14], combined with interplanetary magnetic field and plasma observations made by the Advanced Composition Explorer (ACE) satellite, sitting in the L1 point, close to the Earth. By great storms, we consider those for which the peak of the Dst index was less than -200 nT.…”

Section: Introductionmentioning

confidence: 99%

Great geomagnetic storms in the rise and maximum of solar cycle 23

Lago¹,

Vieira²,

Echer³

et al. 2004

Braz. J. Phys.

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Geomagnetic storms are intervals of time when a sufficiently intense and long-lasting interplanetary convection electric field leads, through a substantial injection of energy into the magnetosphere-ionosphere system, to an intensified ring current, strong enough to exceed some key threshold of the quantifying storm time Dst index. We have studied all the 9 great magnetic storms (peak Dst < -200 nT) observed during the rise and maximum of solar cycle 23 (from 1997 to early 2001), in order to identify their solar and interplanetary causes. Apart of one storm occurred during the period without observations from the Solar and Heliospheric Observatory (SOHO), all of them were related to coronal mass ejections observed by the Large Angle and Spectroscopic Coronagraph (LASCO). The sources of interplanetary southward magnetic field, Bs, responsible for the occurrence of the storms were related to the intensified shock/sheath field, interplanetary magnetic cloud's field, or the combination of sheath-cloud or sheath-ejecta field. It called our attention the fact that one of the events was related to a slow CME, with CME expansion speed not greater than 550 km/s. The purpose of this paper is to address the main sources of large geomagnetic disturbances using the current satellite capability available. As a general conclusion, we found that shock/sheath compressed fields are the most important interplanetary causes of great magnetic storms during this period.

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The Large Angle Spectroscopic Coronagraph (LASCO)

Cited by 2,565 publications

References 5 publications

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Space Weather: Physics, Effects and Predictability

Great geomagnetic storms in the rise and maximum of solar cycle 23

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