On the stellar origin of low energy cosmic rays

The large solar flares associated with cosmic-ray events release total bolometric energies in the region 1024-1 0 25 J. This is of the order 10~5-10~6 of the normal bolometric energy emission of the Sun. The condition of the M and K type stars when they flare is entirely different; the rate of energy release during the flare is of the same order as the normal energy release of the star in the quiescent condition. Although these dwarf stars are in a markedly different evolutionary condition compared with the Sun recent simultaneous radio and optical observations of the flares have given decisive indications that the physical processes, involving magnetic field collapse of several hundredths of a tesla, must be similar to the flare mechanism in the Sun. Adopting the factor, which has been determined empirically in the case of the Sun, for the conversion of flare energy to cosmic-ray energy, estimates are made of the fraction of galactic cosmic rays which may be generated in the flares on the M and K type stars. It is shown that these stars may be the major source of the galactic cosmic rays for energies from 106-3 x 108 eV and that the K type stars may contribute one fifth of the total cosmic-ray energy up to 109 eV.

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

10.5194/epsc2020-818 ◽

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

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.&#160; 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&#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.&#160; 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&#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. Despite the importance of Galactic cosmic rays, their chemical signature in the atmospheres&#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.

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Eleven-year modulation of galactic cosmic rays in interplanetary space

Canadian Journal of Physics ◽

10.1139/p68-373 ◽

1968 ◽

Vol 46 (10) ◽

pp. S879-S882 ◽

Cited By ~ 2

Author(s):

A. N. Chaeakhchyan ◽

T. N. Charakhchyan

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Large Scale ◽

Interplanetary Space ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Magnetic Clouds ◽

The Sun ◽

Cosmic Ray Intensity ◽

Stationary Level

Almost the whole increase in the cosmic-ray intensity in the stratosphere during the period of decreasing solar activity (1960–64) was composed of a number of individual events occurring at intervals of 6–12 months. This phenomenon is almost entirely due to the corresponding decrease of solar activity (according to the sunspot number).Several interesting cases were found when solar-activity decreases to a new stationary level took place rapidly (within several days). After such events the cosmic-ray intensity gradually increased to reach a stationary level over a period of about two months. The time, tst, during which the cosmic-ray intensity in interplanetary space (after the above-mentioned events on the sun) approaches a stationary value is about 40, 60, and 80 days according to observations in 1961, 1963, and 1964 respectively.Some results have been obtained on the large-scale magnetic "clouds" which modulate the galactic cosmic rays in interplanetary space: (a) The velocity of propagation of these magnetic clouds is [Formula: see text]. According to the data on u and tst the radius of the sphere around the sun, r, within which the cosmic rays are modulated depends little on solar activity and is equal to 10–15 AU. (b) The density of magnetic clouds in space is either independent of the distance to the sun or decreases less rapidly than the inverse square law suggested by conservation of clouds.[Formula: see text]

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Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

Science Advances ◽

10.1126/sciadv.aax3793 ◽

2019 ◽

Vol 5 (9) ◽

pp. eaax3793 ◽

Cited By ~ 16

Author(s):

◽

Q. An ◽

R. Asfandiyarov ◽

P. Azzarello ◽

P. Bernardini ◽

...

Keyword(s):

Cosmic Rays ◽

Cosmic Radiation ◽

Precise Measurement ◽

Milky Way ◽

Spectral Feature ◽

Dark Matter Particle ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Proton Spectrum ◽

First Time

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

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Atmospheric production and transport of 7Be activity by cosmic rays: Modelling with the chemistry-climate model SOCOLv3.0 and comparison with direct measurements

10.5194/egusphere-egu21-2287 ◽

2021 ◽

Author(s):

Kseniia Golubenko ◽

Eugene Rozanov ◽

Genady Kovaltsov ◽

Ari-Pekka Leppänen ◽

Ilya Usoskin

Keyword(s):

Cosmic Rays ◽

Climate Changes ◽

Climate Model ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Cosmogenic Isotopes ◽

Cosmogenic Isotope ◽

The Past ◽

Direct Measurements ◽

First Results

We present the first results of modelling of the short-living cosmogenic isotope 7Be production, deposition, and transport using the chemistry-climate model SOCOLv3.0 aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme, &#160;based on gas tracers with and without nudging to the known meteorological fields. Production of 7Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of 7Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope 7Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002&#8211;2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past.&#160;

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Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

Annual Review of Nuclear and Particle Science ◽

10.1146/annurev-nucl-101917-021151 ◽

2018 ◽

Vol 68 (1) ◽

pp. 377-404 ◽

Cited By ~ 12

Author(s):

Vincent Tatischeff ◽

Stefano Gabici

Keyword(s):

Cosmic Rays ◽

Light Element ◽

Cosmic Ray ◽

Nuclear Interaction ◽

Galactic Cosmic Rays ◽

Light Elements ◽

Halo Stars ◽

The Standard Model ◽

Low Metallicity ◽

Galactic Cosmic Ray

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

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Ulysses COSPIN observations of cosmic rays and solar energetic particles from the South Pole to the North Pole of the Sun during solar maximum

Annales Geophysicae ◽

10.5194/angeo-21-1217-2003 ◽

2003 ◽

Vol 21 (6) ◽

pp. 1217-1228 ◽

Cited By ~ 56

Author(s):

R. B. McKibben ◽

J. J. Connell ◽

C. Lopate ◽

M. Zhang ◽

J. D. Anglin ◽

...

Keyword(s):

Cosmic Rays ◽

Solar Maximum ◽

Cosmic Ray ◽

Energetic Particles ◽

Solar Energetic Particles ◽

Polar Regions ◽

The Sun ◽

The South ◽

The North ◽

Inner Heliosphere

Abstract. In 2000–2001 Ulysses passed from the south to the north polar regions of the Sun in the inner heliosphere, providing a snapshot of the latitudinal structure of cosmic ray modulation and solar energetic particle populations during a period near solar maximum. Observations from the COSPIN suite of energetic charged particle telescopes show that latitude variations in the cosmic ray intensity in the inner heliosphere are nearly non-existent near solar maximum, whereas small but clear latitude gradients were observed during the similar phase of Ulysses’ orbit near the 1994–95 solar minimum. At proton energies above ~10 MeV and extending up to >70 MeV, the intensities are often dominated by Solar Energetic Particles (SEPs) accelerated near the Sun in association with intense solar flares and large Coronal Mass Ejections (CMEs). At lower energies the particle intensities are almost constantly enhanced above background, most likely as a result of a mix of SEPs and particles accelerated by interplanetary shocks. Simultaneous high-latitude Ulysses and near-Earth observations show that most events that produce large flux increases near Earth also produce flux increases at Ulysses, even at the highest latitudes attained. Particle anisotropies during particle onsets at Ulysses are typically directed outwards from the Sun, suggesting either acceleration extending to high latitudes or efficient cross-field propagation somewhere inside the orbit of Ulysses. Both cosmic ray and SEP observations are consistent with highly efficient transport of energetic charged particles between the equatorial and polar regions and across the mean interplanetary magnetic fields in the inner heliosphere.Key words. Interplanetary physics (cosmic rays) – Solar physics, astrophysics and astronomy (energetic particles; flares and mass ejections)

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Short- and Medium-Term Induced Ionization in the Earth Atmosphere by Galactic and Solar Cosmic Rays

International Journal of Atmospheric Sciences ◽

10.1155/2013/184508 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Alexander Mishev

Keyword(s):

Cosmic Rays ◽

Cosmic Ray ◽

Ground Level ◽

Galactic Cosmic Rays ◽

Earth Atmosphere ◽

Medium Term ◽

Ground Level Enhancement ◽

Solar Cosmic Rays ◽

The Earth ◽

Ionization Effect

The galactic cosmic rays are the main source of ionization in the troposphere of the Earth. Solar energetic particles of MeV energies cause an excess of ionization in the atmosphere, specifically over polar caps. The ionization effect during the major ground level enhancement 69 on January 20, 2005 is studied at various time scales. The estimation of ion rate is based on a recent numerical model for cosmic-ray-induced ionization. The ionization effect in the Earth atmosphere is obtained on the basis of solar proton energy spectra, reconstructed from GOES 11 measurements and subsequent full Monte Carlo simulation of cosmic-ray-induced atmospheric cascade. The evolution of atmospheric cascade is performed with CORSIKA 6.990 code using FLUKA 2011 and QGSJET II hadron interaction models. The atmospheric ion rate is explicitly obtained for various latitudes, namely, 40°N, 60°N and 80°N. The time evolution of obtained ion rates is presented. The short- and medium-term ionization effect is compared with the average effect due to galactic cosmic rays. It is demonstrated that ionization effect is significant only in subpolar and polar atmosphere during the major ground level enhancement of January 20, 2005. It is negative in troposphere at midlatitude, because of the accompanying Forbush effect.

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A reevaluation of the atmospheric pressure dependence of secondary cosmic-ray neutrons in the context of Cosmic-Ray Neutron Sensing

10.5194/egusphere-egu21-10602 ◽

2021 ◽

Author(s):

Jannis Weimar ◽

Paul Schattan ◽

Martin Schrön ◽

Markus Köhli ◽

Rebecca Gugerli ◽

...

Keyword(s):

Cosmic Rays ◽

Hydrogen Content ◽

Atmospheric Pressure ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Atmospheric Air ◽

Neutron Intensity ◽

The Earth ◽

Wide Range ◽

Primary Cosmic Rays

Secondary cosmic-ray neutrons may be effectively used as a proxy for environmental hydrogen content at the hectare scale. These neutrons are generated mostly in the upper layers of the atmosphere within particle showers induced by galactic cosmic rays and other secondary particles. Below 15 km altitude their intensity declines as primary cosmic rays become less abundant and the generated neutrons are attenuated by the atmospheric air. At the earth surface, the intensity of secondary cosmic-ray neutrons heavily depends on their attenuation within the atmosphere, i.e. the amount of air the neutrons and their precursors pass through. Local atmospheric pressure measurements present an effective means to account for the varying neutron attenuation potential of the atmospheric air column above the neutron sensor. Pressure variations possess the second largest impact on the above-ground epithermal neutron intensity. Thus, using epithermal neutrons to infer environmental hydrogen content requires precise knowledge on how to correct for atmospheric pressure changes.We conducted several short-term field experiments in saturated environments and at different altitudes, i.e. different pressure states to observe the neutron intensity pressure relation over a wide range of pressure values. Moreover, we used long-term measurements above glaciers in order to monitor the local dependence of neutron intensities and pressure in a pressure range typically found in Cosmic-Ray Neutron Sensing. The results are presented along with a broad Monte Carlo simulation campaign using MCNP 6. In these simulations, primary cosmic rays are released above the earth atmosphere at different cut-off rigidities capturing the whole evolution of cosmic-ray neutrons from generation to attenuation and annihilation. The simulated and experimentally derived pressure relation of cosmic-ray neutrons is compared to those of similar studies and assessed in the light of an appropriate atmospheric pressure correction for Cosmic-Ray Neutron Sensing.

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Influence of supernovae, gamma-ray bursts, solar flares, and cosmic rays on the terrestrial environment

Global Catastrophic Risks ◽

10.1093/oso/9780198570509.003.0017 ◽

2008 ◽

Author(s):

Arnon Dar

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Gamma Ray ◽

Cosmic Ray ◽

Gamma Ray Bursts ◽

The Sun ◽

Terrestrial Environment ◽

The Earth ◽

The Galaxy ◽

Threat To Life

Changes in the solar neighbourhood due to the motion of the sun in the Galaxy, solar evolution, and Galactic stellar evolution influence the terrestrial environment and expose life on the Earth to cosmic hazards. Such cosmic hazards include impact of near-Earth objects (NEOs), global climatic changes due to variations in solar activity and exposure of the Earth to very large fluxes of radiations and cosmic rays from Galactic supernova (SN) explosions and gamma-ray bursts (GRBs). Such cosmic hazards are of low probability, but their influence on the terrestrial environment and their catastrophic consequences, as evident from geological records, justify their detailed study, and the development of rational strategies, which may minimize their threat to life and to the survival of the human race on this planet. In this chapter I shall concentrate on threats to life from increased levels of radiation and cosmic ray (CR) flux that reach the atmosphere as a result of (1) changes in solar luminosity, (2) changes in the solar environment owing to the motion of the sun around the Galactic centre and in particular, owing to its passage through the spiral arms of the Galaxy, (3) the oscillatory displacement of the solar system perpendicular to the Galactic plane, (4) solar activity, (5) Galactic SN explosions, (6) GRBs, and (7) cosmic ray bursts (CRBs). The credibility of various cosmic threats will be tested by examining whether such events could have caused some of the major mass extinctions that took place on planet Earth and were documented relatively well in the geological records of the past 500 million years (Myr). A credible claim of a global threat to life from a change in global irradiation must first demonstrate that the anticipated change is larger than the periodical changes in irradiation caused by the motions of the Earth, to which terrestrial life has adjusted itself. Most of the energy of the sun is radiated in the visible range. The atmosphere is highly transparent to this visible light but is very opaque to almost all other bands of the electromagnetic spectrum except radio waves, whose production by the sun is rather small.

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The Source Composition of Galactic Cosmic Rays as Possibly Originated from the Dust in the Circumstellar and Interstellar Space

International Astronomical Union Colloquium ◽

10.1017/s0252921100067257 ◽

1991 ◽

Vol 126 ◽

pp. 433-436

Author(s):

Kunitomo Sakurai

Keyword(s):

Chemical Composition ◽

Cosmic Rays ◽

Solar Atmosphere ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Interstellar Space ◽

Interstellar Clouds ◽

Supernova Explosions ◽

Siderophile Elements

AbstractThe chemical composition of galactic cosmic rays in their sources is similar to that of interstellar clouds or grains which are relatively enriched in refractory and siderophile elements as compared with the chemical composition of the solar atmosphere. Taking into account this fact, it is shown that the cosmic ray source matter can be identified as the dust or grains observed in the envelopes of red supergiant stars or the matter originally ejected from supernova explosions.

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