scholarly journals Delay in solar energetic particle onsets at high heliographic latitudes

2003 ◽  
Vol 21 (6) ◽  
pp. 1367-1375 ◽  
Author(s):  
S. Dalla ◽  
A. Balogh ◽  
S. Krucker ◽  
A. Posner ◽  
R. Müller-Mellin ◽  
...  
Keyword(s):  
Solar Physics ◽  
Solar Energetic Particle ◽  
Interplanetary Shock ◽  
Energetic Particles ◽  
Release Time ◽  
The Sun ◽  
Interplanetary Physics ◽  
Particle Speed ◽  
The Difference ◽  
Path Lengths

Abstract. Ulysses observations have shown that solar energetic particles (SEPs) can easily reach high heliographic latitudes. To obtain information on the release and propagation of SEPs prior to their arrival at Ulysses, we analyse the onsets of nine large high-latitude particle events. We measure the onset times in several energy channels, and plot them versus inverse particle speed. This allows us to derive an experimental path length and time of release from the solar atmosphere. We repeat the procedure for near-Earth observations by Wind and SOHO. We find that the derived path lengths at Ulysses are 1.06 to 2.45 times the length of a Parker spiral magnetic field line connecting the spacecraft to the Sun. The time of particle release from the Sun is between 100 and 350 min later than the release time derived from in-ecliptic measurements. We find no evidence of correlation between the delay in release and the inverse of the speed of the CME associated with the event, or the inverse of the speed of the corresponding interplanetary shock. The main parameter determining the magnitude of the delay appears to be the difference in latitude between the flare and the footpoint of the spacecraft.Key words. Interplanetary physics (energetic particles) – Solar physics, astrophysics and astronomy (energetic particles, flares and mass ejections)

scholarly journals From the Sun’s south to the north pole – Ulysses COSPIN/LET composition measurements at solar maximum

2003 ◽  
Vol 21 (6) ◽  
pp. 1383-1391 ◽  
Author(s):  
M. Y. Hofer ◽  
R. G. Marsden ◽  
T. R. Sanderson ◽  
C. Tranquille
Keyword(s):  
Energetic Particle ◽  
Solar Physics ◽  
Solar Energetic Particle ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Elemental Abundance ◽  
Interplanetary Shocks ◽  
Activity Maximum ◽  
Interplanetary Physics ◽  
Inner Heliosphere

Abstract. Based on elemental abundance ratios derived from the Ulysses COSPIN/LET measurements, we classified the energetic particle populations during and after the socalled Fast Latitude Scan – the time period during which the Ulysses spacecraft traveled from the highest heliolatitude south to maximum northern latitude, i.e. 27 November 2000 to 13 October 2001 – as being mixed between solar energetic particles (major component) and particles accelerated at stream interaction regions. During the fast latitude scan, the Ulysses spacecraft made the first transit in heliolatitude from pole to pole during solar activity maximum conditions, providing a unique opportunity to acquire energetic particle composition data over a maximum range of heliolatitudes in the inner heliosphere. At low latitudes, based on our elemental abundance analysis, we found that while solar energetic particles dominated, there were indications for particle acceleration at single compression regions in a few instances. In the high heliolatitude range the observed elemental particle compositions are mainly of the solar energetic particle type. Within the statistical errors, the observed abundance ratios were independent of latitude, and were characteristic of solar energetic particles. These observations raise an important question for the theories of particle propagation in the inner heliosphere. The daily elemental abundance ratios of S/O, Mg/O and Si/O shown here are the first measured ratios at high heliolatitudes in the energy range from 13.0 to 30.0 MeV/n.Key words. Interplanetary physics (energetic particles; interplanetary shocks) – Solar physics, astrophysics and astronomy (flares and mass ejections)

scholarly journals ERNE observations of energetic particles associated with Earth-directed coronal mass ejections in April and May, 1997

2000 ◽  
Vol 18 (11) ◽  
pp. 1373-1381 ◽  
Author(s):  
A. Anttila ◽  
T. Sahla
Keyword(s):  
Coronal Mass Ejections ◽  
Energetic Particle ◽  
Solar Physics ◽  
Energetic Particles ◽  
Intensity Increase ◽  
Angle Distribution ◽  
The Sun ◽  
Interplanetary Shocks ◽  
Directional Information ◽  
Interplanetary Physics

Abstract. Two Earth-directed coronal mass ejections (CMEs), which were most effective in energetic (~1–50 MeV) particle acceleration during the first 18 months since the Solar and Heliospheric Observatory (SOHO) launch, occurred on April 7 and May 12, 1997. In the analysis of these events we have deconvoluted the injection spectrum of energetic protons by using the method described by Anttila et al. In order to apply the method developed earlier for data of a rotating satellite (Geostationary Operational Environmental Satellites, GOES), we first had to develop a method to calculate the omnidirectional energetic particle intensities from the observations of Energetic and Relativistic Nuclei and Electrons (ERNE), which is an energetic particle detector onboard the three-axis stabilized SOHO spacecraft. The omnidirectional intensities are calculated by fitting an exponential pitch angle distribution from directional information of energetic protons observed by ERNE. The results of the analysis show that, compared to a much faster and more intensive CMEs observed during the previous solar maximum, the acceleration efficiency decreases fast when the shock propagates outward from the Sun. The particles injected at distances <0.5 AU from the Sun dominate the particle flux during the whole period, when the shock propagates to the site of the spacecraft. The main portion of particles injected by the shock during its propagation further outward from the Sun are trapped around the shock, and are seen as an intensity increase at the time of the shock passage.Key words: Interplanetary physics (interplanetary shocks) – Solar physics, astrophysics and astronomy (energetic particles; flares and mass ejections)

scholarly journals Transforming in-situ observations of CME-driven shock accelerated protons into the shock's reference frame.

2005 ◽  
Vol 23 (5) ◽  
pp. 1931-1941 ◽  
Author(s):  
I. M. Robinson ◽  
G. M. Simnett
Keyword(s):  
Solar Physics ◽  
Solar Energetic Particle ◽  
Transport Processes ◽  
Solar Energetic Particle Event ◽  
The Sun ◽  
Proton Acceleration ◽  
Angle Scattering ◽  
Peak Energy ◽  
In Situ Observations

Abstract. We examine the solar energetic particle event following solar activity from 14, 15 April 2001 which includes a "bump-on-the-tail" in the proton energy spectra at 0.99 AU from the Sun. We find this population was generated by a CME-driven shock which arrived at 0.99 AU around midnight 18 April. As such this population represents an excellent opportunity to study in isolation, the effects of proton acceleration by the shock. The peak energy of the bump-on-the-tail evolves to progressively lower energies as the shock approaches the observing spacecraft at the inner Lagrange point. Focusing on the evolution of this peak energy we demonstrate a technique which transforms these in-situ spectral observations into a frame of reference co-moving with the shock whilst making allowance for the effects of pitch angle scattering and focusing. The results of this transform suggest the bump-on-the-tail population was not driven by the 15 April activity but was generated or at least modulated by a CME-driven shock which left the Sun on 14 April. The existence of a bump-on-the-tail population is predicted by models in Rice et al. (2003) and Li et al. (2003) which we compare with observations and the results of our analysis in the context of both the 14 April and 15 April CMEs. We find an origin of the bump-on-the-tail at the 14 April CME-driven shock provides better agreement with these modelled predictions although some discrepancy exists as to the shock's ability to accelerate 100 MeV protons. Keywords. Solar physics, astrophysics and astronomy (Energetic particles; Flares and mass ejections) – Space plasma physics (Transport processes)

scholarly journals Detection of zero anisotropy at 5.2 AU during the November 1998 solar particle event: Ulysses Anisotropy Telescopes observations

2000 ◽  
Vol 18 (3) ◽  
pp. 277-284 ◽  
Author(s):  
S. Dalla ◽  
A. Balogh
Keyword(s):  
Solar Physics ◽  
Energetic Particles ◽  
Space Plasma Physics ◽  
Heliographic Latitude ◽  
Particle Event ◽  
Solar Particle Event ◽  
High Proton ◽  
Interplanetary Physics ◽  
Instruments And Techniques ◽  
First Time

Abstract. For the first time during the mission, the Anisotropy Telescopes instrument on board the Ulysses spacecraft measured constant zero anisotropy of protons in the 1.3-2.2 MeV energy range, for a period lasting more than three days. This measurement was made during the energetic particle event taking place at Ulysses between 25 November and 15 December 1998, an event characterised by constant high proton fluxes within a region delimited by two interplanetary forward shocks, at a distance of 5.2 AU from the Sun and heliographic latitude of 17°S. We present the ATs results for this event and discuss their possible interpretation and their relevance to the issue of intercalibration of the two telescopes.Key words: Interplanetary physics (energetic particles) - Solar physics, astrophysics and astronomy (energetic particles) - Space plasma physics (instruments and techniques)

scholarly journals Long-duration high-energy proton events observed by GOES in October 1989

1998 ◽  
Vol 16 (8) ◽  
pp. 921-930 ◽  
Author(s):  
A. Anttila ◽  
L. G. Kocharov ◽  
J. Torsti ◽  
R. Vainio
Keyword(s):  
Shock Waves ◽  
Solar Rotation ◽  
Solar Physics ◽  
Interplanetary Shock ◽  
High Energy ◽  
Injection Rate ◽  
Angular Distance ◽  
Seed Particle ◽  
Long Duration ◽  
Interplanetary Physics

Abstract. We consider the prolonged injection of the high-energy (>10 MeV) protons during the three successive events observed by GOES in October 1989. We apply a solar-rotation-stereoscopy approach to study the injection of the accelerated particles from the CME-driven interplanetary shock waves in order to find out how the effectiveness of the particle acceleration and/or escape depends on the angular distance from the shock axis. We use an empirical model for the proton injection at the shock and a standard model of the interplanetary transport. The model can reproduce rather well the observed intensity–time profiles of the October 1989 events. The deduced proton injection rate is highest at the nose of the shock; the injection spectrum is always harder near the Sun. The results seem to be consistent with the scheme that the CME-driven interplanetary shock waves accelerate a seed particle population of coronal origin.Key words. Interplanetary physics · Energetic particles · Solar physics · astrophysics and astronomy · Flares and mass ejections

scholarly journals A survey of <sup>3</sup>He enhancements at 2–20 MeV/nucleon: Ulysses COSPIN/LET

2003 ◽  
Vol 21 (6) ◽  
pp. 1245-1248 ◽  
Author(s):  
C. Tranquille ◽  
R. G. Marsden ◽  
T. R. Sanderson ◽  
M. Y. Hofer
Keyword(s):  
Heliocentric Distance ◽  
Solar Physics ◽  
Heavy Ion ◽  
Energetic Particles ◽  
Data Set ◽  
Spatial Coverage ◽  
Interplanetary Physics ◽  
Recent Attention ◽  
Flare Site ◽  
Inner Heliosphere

Abstract. We present the results of a survey of enhancements in the ratio of 3He/4 He as measured by the COSPIN/LET instrument on board the Ulysses spacecraft in the energy range 2–20 MeV/n. In the context of this study, all ratios of 3He/4 He above 0.05 are considered to be enhanced compared with the solar system value of ~0.0004. Previous studies have shown that enhanced fluxes of 3He are frequently associated with small, impulsive solar flare events in which the observer is well connected to the flare site. These events also often show enrichments in heavy ion composition compared with standard coronal values. Recent attention has also focused on 3He enrichments as evidence for re-acceleration of remnant particle populations that are present in the inner heliosphere following periods of enhanced solar activity. For this study, we have examined the Ulysses data set from launch (October 1990) up to the present, representing a full solar cycle. The spatial coverage extends from 1–5.4 AU in heliocentric distance, and effectively includes the complete range of heliomagnetic latitudes from pole to pole. We have identified 12 periods of enhanced 3He/4 He, occurring at heliocentric distances out to 5 AU, and heliolatitudes up to 48°. We investigate the characteristics of the events, many of which last for several days, in order to establish possible origins.Key words. Interplanetary physics (energetic particles) – Solar physics, astrophysics and astronomy (energetic particles; flares and mass ejections)

scholarly journals Case studies of space weather events from their launching on the Sun to their impacts on power systems on the Earth

2002 ◽  
Vol 20 (7) ◽  
pp. 1073-1079 ◽  
Author(s):  
H.-L. Lam ◽  
D. H. Boteler ◽  
L. Trichtchenko
Keyword(s):  
Power Systems ◽  
Case Studies ◽  
Space Weather ◽  
Solar Physics ◽  
The United States ◽  
The Sun ◽  
Geomagnetically Induced Currents ◽  
Interplanetary Magnetic Fields ◽  
Weather Events ◽  
Interplanetary Physics

Abstract. Active geomagnetic conditions on 12–13, 15–16, and 22–23 September 1999 resulted in geomagnetically induced currents (GIC) measurable in power systems in Canada and the United States. Different solar origins for these three events gave rise to dissimilar interplanetary signatures. We used these events to present three case studies, each tracing an entire space weather episode from its inception on the Sun, propagation through the interplanetary medium, manifestation on the ground as intense magnetic and electric fluctuations, and its eventual impact on technological systems.Key words. Geomagnetism and paleomagnetism (rapid time variations) – Interplanetary physics (interplanetary magnetic fields) – Solar physics, astrophysics, and astronomy (flares and mass ejections)

scholarly journals The Solar and Heliospheric Observatory

1984 ◽  
Vol 86 ◽  
pp. 155-158 ◽  
Author(s):  
Giancarlo Noci
Keyword(s):  
Solar Physics ◽  
Grazing Incidence ◽  
Spectral Irradiance ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Constant ◽  
Heliospheric Observatory ◽  
Explorer Mission ◽  
Solar Dynamics ◽  
Euv Spectrum

In the past years several space missions have been proposed for the study of the Sun and of the Heliosphere. These missions were intended to clarify various different aspects of solar physics. For example, the GRIST (Grazing Incidence Solar Telescope) mission was intended as a means to improve our knowledge of the upper transition region and low corona through the detection of the solar EUV spectrum with a spatial resolution larger than in previous missions; the DISCO (Dual Spectral Irradiance and Solar Constant Orbiter) and SDO (Solar Dynamics Observatory) missions were proposed to gat observational data about the solar oscillations better than those obtained from ground based instruments; the SOHO (Solar and Heliospheric Observatory) mission was initially proposed to combine the properties of GRIST with the study of the extended corona (up to several radii of heliocentric distance) by observing the scattered Ly-alpha and OVI radiation, which was also the basis of the SCE (Solar Corona Explorer) mission proposal; the development of the interest about the variability of the Sun, both in itself and for its consequences in the history of the Earth, led to propose observations of the solar constant (included in DISCO).

scholarly journals Unusual enhancement of ~ 30 MeV proton flux in an ICME sheath region

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Mitsuo Oka ◽  
Takahiro Obara ◽  
Nariaki V. Nitta ◽  
Seiji Yashiro ◽  
Daikou Shiota ◽  
...  
Keyword(s):  
Shock Front ◽  
Energetic Particle ◽  
Leading Edge ◽  
Solar Energetic Particle ◽  
Interplanetary Shock ◽  
Proton Event ◽  
Sheath Region ◽  
Time Profiles ◽  
Energetic Particle Flux ◽  
Mev Protons

AbstractIn gradual Solar Energetic Particle (SEP) events, shock waves driven by coronal mass ejections (CMEs) play a major role in accelerating particles, and the energetic particle flux enhances substantially when the shock front passes by the observer. Such enhancements are historically referred to as Energetic Storm Particle (ESP) events, but it remains unclear why ESP time profiles vary significantly from event to event. In some cases, energetic protons are not even clearly associated with shocks. Here, we report an unusual, short-duration proton event detected on 5 June 2011 in the compressed sheath region bounded by an interplanetary shock and the leading edge of the interplanetary CME (or ICME) that was driving the shock. While < 10 MeV protons were detected already at the shock front, the higher-energy (> 30 MeV) protons were detected about four hours after the shock arrival, apparently correlated with a turbulent magnetic cavity embedded in the ICME sheath region.

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