Gradient of galactic cosmic rays normal to the solar equatorial plane

1968 ◽  
Vol 46 (10) ◽  
pp. S981-S984 ◽  
Author(s):  
D. Patel ◽  
V. Sababhai ◽  
G. Subramanian
Keyword(s):  
Magnetic Field ◽  
Energy Spectrum ◽  
Cosmic Rays ◽  
Interplanetary Magnetic Field ◽  
Equatorial Plane ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Cosmic Ray Intensity ◽  
Positive Exponent ◽  
Ray Density

Predictions concerning the anisotropy of galactic cosmic rays due to a gradient of cosmic-ray density perpendicular to the solar equatorial plane have been verified experimentally as follows. (1) The energy spectrum of the variation of the semidiurnal component has a positive exponent. (2) The diurnal and the semidiurnal components are oriented with respect to the interplanetary magnetic field. (3) A deficiency of cosmic-ray intensity, Tmin, is observed along the direction of the interplanetary magnetic field on days when the energy spectrum of the diurnal variation has an exponent different from zero.

scholarly journals The Ulysses fast latitude scans: COSPIN/KET results

2003 ◽  
Vol 21 (6) ◽  
pp. 1275-1288 ◽  
Author(s):  
B. Heber ◽  
G. Sarri ◽  
G. Wibberenz ◽  
C. Paizis ◽  
P. Ferrando ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Solar Magnetic Field ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Solar Particle Events ◽  
Interplanetary Magnetic Fields ◽  
Solar Particle ◽  
Interplanetary Physics

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in December 1997, and its second fast latitude scan in September 2000. In contrast to the first fast latitude scan in 1994/1995, during the second fast latitude scan solar activity was close to maximum. The solar magnetic field reversed its polarity around July 2000. While the first latitude scan mainly gave a snapshot of the spatial distribution of galactic cosmic rays, the second one is dominated by temporal variations. Solar particle increases are observed at all heliographic latitudes, including events that produce >250 MeV protons and 50 MeV electrons. Using observations from the University of Chicago’s instrument on board IMP8 at Earth, we find that most solar particle events are observed at both high and low latitudes, indicating either acceleration of these particles over a broad latitude range or an efficient latitudinal transport. The latter is supported by "quiet time" variations in the MeV electron background, if interpreted as Jovian electrons. No latitudinal gradient was found for >106 MeV galactic cosmic ray protons, during the solar maximum fast latitude scan. The electron to proton ratio remains constant and has practically the same value as in the previous solar maximum. Both results indicate that drift is of minor importance. It was expected that, with the reversal of the solar magnetic field and in the declining phase of the solar cycle, this ratio should increase. This was, however, not observed, probably because the transition to the new magnetic cycle was not completely terminated within the heliosphere, as indicated by the Ulysses magnetic field and solar wind measurements. We argue that the new A<0-solar magnetic modulation epoch will establish itself once both polar coronal holes have developed.Key words. Interplanetary physics (cosmic rays; energetic particles; interplanetary magnetic fields)

scholarly journals The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds

Galaxies ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 48 ◽  
Author(s):  
Peter L. Biermann ◽  
Philipp P. Kronberg ◽  
Michael L. Allen ◽  
Athina Meli ◽  
Eun-Suk Seo
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Space Station ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Starburst Galaxy ◽  
Supergiant Star

We propose that the high energy Cosmic Ray particles up to the upturn commonly called the ankle, from around the spectral turn-down commonly called the knee, mostly come from Blue Supergiant star explosions. At the upturn, i.e., the ankle, Cosmic Rays probably switch to another source class, most likely extragalactic sources. To show this we recently compiled a set of Radio Supernova data where we compute the magnetic field, shock speed and shock radius. This list included both Blue and Red Supergiant star explosions; both data show the same magnetic field strength for these two classes of stars despite very different wind densities and velocities. Using particle acceleration theory at shocks, those numbers can be transformed into characteristic ankle and knee energies. Without adjusting any free parameters both of these observed energies are directly indicated by the supernova data. In the next step in the argument, we use the Supernova Remnant data of the starburst galaxy M82. We apply this analysis to Blue Supergiant star explosions: The shock will race to their outer edge with a magnetic field that is observed to follow over several orders of magnitude B ( r ) × r ∼ c o n s t . , with in fact the same magnetic field strength for such stellar explosions in our Galaxy, and other galaxies including M82. The speed is observed to be ∼0.1 c out to about 10 16 cm radius in the plasma wind. The Supernova shock can run through the entire magnetic plasma wind region at full speed all the way out to the wind-shell, which is of order parsec scale in M82. We compare and identify the Cosmic Ray spectrum in other galaxies, in the starburst galaxy M82 and in our Galaxy with each other; we suggest how Blue Supergiant star explosions can provide the Cosmic Ray particles across the knee and up to the ankle energy range. The data from the ISS-CREAM (Cosmic Ray Energetics and Mass Experiment at the International Space Station) mission will test this cosmic ray concept which is reasonably well grounded in two independent radio supernova data sets. The next step in developing our understanding will be to obtain future more accurate Cosmic Ray data near to the knee, and to use unstable isotopes of Cosmic Ray nuclei at high energy to probe the “piston” driving the explosion. We plan to incorporate these data with the physics of the budding black hole which is probably forming in each of these stars.

scholarly journals Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: ULYSSES COSPIN/KET and neutron monitor network observations

2003 ◽  
Vol 21 (6) ◽  
pp. 1295-1302 ◽  
Author(s):  
A. V. Belov ◽  
E. A. Eroshenko ◽  
B. Heber ◽  
V. G. Yanke ◽  
A. Raviart ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Neutron Monitor ◽  
Solar Minimum ◽  
Latitudinal Gradient ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Alpha Particles ◽  
Polar Regions

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The Kiel Electron Telescope (KET) measures also protons and alpha-particles in the energy range from 5 MeV/n to >2 GeV/n. To derive radial and latitudinal gradients for >2 GeV/n protons and alpha-particles, data from the Chicago instrument on board IMP-8 and the neutron monitor network have been used to determine the corresponding time profiles at Earth. We obtain a spatial distribution at solar maximum which differs greatly from the solar minimum distribution. A steady-state approximation, which was characterized by a small radial and significant latitudinal gradient at solar minimum, was interchanged with a highly variable one with a large radial and a small – consistent with zero – latitudinal gradient. A significant deviation from a spherically symmetric cosmic ray distribution following the reversal of the solar magnetic field in 2000/2001 has not been observed yet. A small deviation has only been observed at northern polar regions, showing an excess of particles instead of the expected depression. This indicates that the reconfiguration of the heliospheric magnetic field, caused by the reappearance of the northern polar coronal hole, starts dominating the modulation of galactic cosmic rays already at solar maximum.Key words. Interplanetary physics (cosmic rays; energetic particles) – Space plasma physics (charged particle motion and acceleration)

The change in the energy spectrum of galactic cosmic rays over the 11-year solar activity cycle

1968 ◽  
Vol 46 (10) ◽  
pp. S927-S929
Author(s):  
Yu. Stozhkov ◽  
T. N. Charakhchyan
Keyword(s):  
Diffusion Coefficient ◽  
Solar Activity ◽  
Energy Spectrum ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Galactic Cosmic Rays ◽  
Ray Diffusion

The energy spectrum of galactic cosmic rays has been investigated for various periods of the solar activity. In the framework of commonly used ideas about the mechanism of the 11-year variation according to Parker the dependence of the cosmic-ray diffusion coefficient, D, on the particle rigidity, P, was determined. For the form D ≈ vpα the parameter α is found to change during the cycle of the solar activity.[Formula: see text]

scholarly journals The Galactic cosmic ray intensity at the evolving Earth and young exoplanets

2020 ◽  
Author(s):  
Donna Rodgers-Lee ◽  
Aline Vidotto ◽  
Andrew Taylor ◽  
Paul Rimmer ◽  
Turlough Downes
Keyword(s):  
Solar Wind ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
The Sun ◽  
Cosmic Ray Intensity ◽  
Chemical Signature ◽  
Exoplanetary Systems ◽  
Life On Earth ◽  
Galactic Cosmic Ray

&lt;p&gt;Cosmic rays may have contributed to the start of life on Earth. Cosmic rays also influence and contribute to atmospheric electrical circuits, cloud cover and biological mutation rates which are important for the characterisation of exoplanetary systems. The flux of Galactic cosmic rays present at the time when life is thought to have begun on the young Earth or in other young exoplanetary systems is largely determined by the properties of the stellar wind.&amp;#160;&lt;/p&gt; &lt;p&gt;The spectrum of Galactic cosmic rays that we observe at Earth is modulated, or suppressed, by the magnetised solar wind and thus differs from the local interstellar spectrum observed by Voyager 1 and 2 outside of the solar system. Upon reaching 1au, Galactic cosmic rays subsequently interact with the Earth&amp;#8217;s magnetosphere and some of their energy is deposited in the upper atmosphere. The properties of the solar wind, such as the magnetic field strength and velocity profile, evolve with time. Generally, young solar-type stars are very magnetically active and are therefore thought to drive stronger stellar winds.&amp;#160;&lt;/p&gt; &lt;p&gt;Here I will present our recent results which simulate the propagation of Galactic cosmic rays through the heliosphere to the location of Earth as a function of the Sun's life, from 600 Myr to 6 Gyr, in the Sun&amp;#8217;s future. I will specifically focus on the flux of Galactic cosmic rays present at the time when life is thought to have started on Earth (~1 Gyr). I will show that the intensity of Galactic cosmic rays which reached the young Earth, by interacting with the solar wind, would have been greatly reduced in comparison to the present day intensity. I will also discuss the effect that the Sun being a slow/fast rotator would have had on the flux of cosmic rays reaching Earth at early times in the solar system's life.&lt;/p&gt; &lt;p&gt;Despite the importance of Galactic cosmic rays, their chemical signature in the atmospheres&amp;#8217; of young Earth-like exoplanets may not be observable with instruments in the near future. On the other hand, it may instead be possible to detect their chemical signature by observing young warm Jupiters. Thus, I will also discuss the HR 2562b exoplanetary system as a candidate for observing the chemical signature of Galactic cosmic rays in a young exoplanetary atmosphere with upcoming missions such as JWST.&lt;/p&gt;

scholarly journals Precursory signals of Forbush decreases with and without shock wave

2021 ◽  
pp. 57-63
Author(s):  
Dimitra Lingri ◽  
Helen Mavromichalaki ◽  
Anatoly V. Belov ◽  
Eugenia A. Eroshenko
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Interplanetary Magnetic Field ◽  
Selection Criteria ◽  
Forbush Decrease ◽  
Cosmic Ray ◽  
Abrupt Increase ◽  
Cosmic Ray Intensity ◽  
Similarities And Differences ◽  
Solar Disturbances

Many previous studies have shown that before the beginning of a Forbush Decrease (FD) of the cosmic ray intensity, a precursor signal can be observed. All these surveys were focused on FDs that are associated with a sudden storm com- mencement (SSC). In this work we demonstrate that precursors could also be observed in events without a SSC that is determined by an abrupt increase of the interplanetary magnetic field. The type of precursory signals and their diversity among the events are the main purpose of this study. We try to figure out similarities and differences on the signals and the associated events from both categories in the last fifty years, from 1969 to 2019, using the same selection criteria of the under investigation FDs. Simultaneously the orientation of the upcoming solar disturbances in comparison to the way they configure the increase of the interplanetary magnetic field and create these signals are discussed.

Effects of ICMEs on High Energetic Particles as Observed by the Global Muon Detector Network (GMDN)

2017 ◽  
Vol 13 (S335) ◽  
pp. 69-74
Author(s):  
A. Dal Lago ◽  
C. R. Braga ◽  
R. R. S. de Mendonca ◽  
M. Rockenbach ◽  
E. Echer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Lead Times ◽  
Muon Detector ◽  
Crucial Importance ◽  
The Earth

AbstractThe Global Muon Detector Network (GMDN) is composed by four ground cosmic ray detectors distributed around the Earth: Nagoya (Japan), Hobart (Australia), Sao Martinho da Serra (Brazil) and Kuwait city (Kuwait). The network has operated since March 2006. It has been upgraded a few times, increasing its detection area. Each detector is sensitive to muons produced by the interactions of ~50 GeV Galactic Cosmic Rays (GCR) with the Earth′s atmosphere. At these energies, GCR are known to be affected by interplanetary disturbances in the vicinity of the earth. Of special interest are the interplanetary counterparts of coronal mass ejections (ICMEs) and their driven shocks because they are known to be the main origins of geomagnetic storms. It has been observed that these ICMEs produce changes in the cosmic ray gradient, which can be measured by GMDN observations. In terms of applications for space weather, some attempts have been made to use GMDN for forecasting ICME arrival at the earth with lead times of the order of few hours. Scientific space weather studies benefit the most from the GMDN network. As an example, studies have been able to determine ICME orientation at the earth using cosmic ray gradient. Such determinations are of crucial importance for southward interplanetary magnetic field estimates, as well as ICME rotation.

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