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

<p>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. </p> <p>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’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. </p> <p>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’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.</p> <p>Despite the importance of Galactic cosmic rays, their chemical signature in the atmospheres’ 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.</p>

scholarly journals On the heliolatitudinal variation of the galactic cosmic-ray intensity. Comparison with Ulysses measurements

2003 ◽  
Vol 21 (6) ◽  
pp. 1341-1345 ◽  
Author(s):  
G. Exarhos ◽  
X. Moussas
Keyword(s):  
Solar Wind ◽  
Cosmic Rays ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Solar Wind Plasma ◽  
Simple Method ◽  
Cosmic Ray Intensity ◽  
Interplanetary Physics ◽  
Diffusion Convection ◽  
Galactic Cosmic Ray

Abstract. We study the dependence of cosmic rays with heliolatitude using a simple method and compare the results with the actual data from Ulysses and IMP spacecraft. We reproduce the galactic cosmic-ray heliographic latitudinal intensity variations, applying a semi-empirical, 2-D diffusion-convection model for the cosmic-ray transport in the interplanetary space. This model is a modification of our previous 1-D model (Exarhos and Moussas, 2001) and includes not only the radial diffusion of the cosmic-ray particles but also the latitudinal diffusion. Dividing the interplanetary region into "spherical magnetic sectors" (a small heliolatitudinal extension of a spherical magnetized solar wind plasma shell) that travel into the interplanetary space at the solar wind velocity, we calculate the cosmic-ray intensity for different heliographic latitudes as a series of successive intensity drops that all these "spherical magnetic sectors" between the Sun and the heliospheric termination shock cause the unmodulated galactic cosmic-ray intensity. Our results are compared with the Ulysses cosmic-ray measurements obtained during the first pole-to-pole passage from mid-1994 to mid-1995.Key words. Interplanetary physics (cosmic rays; interplanetray magnetic fields; solar wind plasma)

Eleven-year modulation of galactic cosmic rays in interplanetary space

1968 ◽  
Vol 46 (10) ◽  
pp. S879-S882 ◽  
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]

scholarly journals Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

2018 ◽  
Vol 68 (1) ◽  
pp. 377-404 ◽  
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.

scholarly journals Cosmic Ray Evidence for the Magnetic Configuration of the Heliosphere

1981 ◽  
Vol 94 ◽  
pp. 397-398
Author(s):  
H. S. Ahluwalia
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Ground Level ◽  
The Sun ◽  
Ground Level Enhancement ◽  
Solar Cosmic Rays ◽  
Pile Up ◽  
Scattered Component

Sekido and Murakami (1958) proposed the existence of the heliosphere to explain the scattered component of the solar cosmic rays. The heliosphere of their conception is a spherical shell around the sun. The shell contains a highly-irregular magnetic field and serves to scatter the cosmic rays emitted by the sun. It thereby gives rise to an isotropic component of solar cosmic rays, following the maximum in the ground level enhancement (GLE). Meyer et al. (1956) showed that a similar picture applies to the GLE of 23 February 1956. They conclude that the inner and outer radii of the shell should be 1.4 AU and 5 AU respectively. They suggest that a shell is formed by the “pile-up” of the solar wind under pressure exerted by the interstellar magnetic field, as suggested by Davis (1955).

THE SUN AS A SOURCE OF COSMIC RAYS OF INTERMEDIATE ENERGIES

1959 ◽  
Vol 37 (11) ◽  
pp. 1207-1215
Author(s):  
J. Katzman
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
The Sun ◽  
Relative Importance ◽  
Cosmic Ray Intensity ◽  
Intermediate Energies ◽  
Narrow Angle ◽  
The Impact ◽  
Impact Zones

The cosmic ray intensity as measured with an extremely narrow-angle telescope, 1.2 × 10−3 steradians, and with 96 inches of lead as absorber for the period 1 January 1955 to 31 December 1958 shows an increase of 20%. This increase is attributed to particles coming from the sun. It is shown that the change in hour of maximum of the first and second harmonics can be explained by a change in the relative importance of the impact zones. This phenomenon is attributed to a change in the number and polarity of sunspots.

scholarly journals 39. The anisotropy of primary cosmic radiation and the electromagnetic state in interplanetary space

1958 ◽  
Vol 6 ◽  
pp. 377-385
Author(s):  
V. Sarabhai ◽  
N. W. Nerurkar ◽  
S. P. Duggal ◽  
T. S. G. Sastry
Keyword(s):  
Experimental Data ◽  
Cosmic Rays ◽  
Cosmic Radiation ◽  
Interplanetary Space ◽  
Daily Variation ◽  
Cosmic Ray ◽  
The Sun ◽  
Cosmic Ray Intensity ◽  
Daily Variations ◽  
Primary Cosmic Radiation

Study of the anisotropy of cosmic rays from the measurement of the daily variation of meson intensity has demonstrated that there are significant day-today changes in the anisotropy of the radiation. New experimental data pertaining to these changes and their solar and terrestrial relationships are discussed.An interpretation of these changes of anisotropy in terms of the modulation of cosmic rays by streams of matter emitted by the sun is given. In particular, an explanation for the existence of the recently discovered types of daily variations exhibiting day and night maxima respectively, can be found by an extension of some ideas of Alfvén, Nagashima, and Davies. An integrated attempt is made to interpret the known features of the variation of cosmic ray intensity in conformity with ideas developed above.

On the stellar origin of low energy cosmic rays

1975 ◽  
Vol 277 (1270) ◽  
pp. 489-501 ◽  
Keyword(s):  
Cosmic Rays ◽  
Energy Release ◽  
Solar Flares ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Optical Observations ◽  
Energy Estimates ◽  
The Sun ◽  
Dwarf Stars ◽  
Evolutionary Condition

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.

Galactic cosmic ray induced ionisation on Venus and its effect on cloud droplet stability

2020 ◽  
Author(s):  
Martin Airey ◽  
Giles Harrison ◽  
Karen Aplin ◽  
Christian Pfrang
Keyword(s):  
Cosmic Rays ◽  
Evaporation Rate ◽  
Cloud Droplet ◽  
Ccd Camera ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Cloud Droplets ◽  
Droplet Stability ◽  
Ion Production ◽  
Galactic Cosmic Ray

<p>Galactic cosmic rays are ubiquitous in solar system atmospheres. On Venus, the altitude of peak ion production due to cosmic rays (the Pfotzer-Regener maximum) occurs at ~63 km, within the optically thick region of the upper clouds. This indicates the possibility of electrical effects on droplets within Venusian clouds. Motivated by this, our VENI (Venusian Electricity, Nephology, and Ionisation) project explores effects of galactic cosmic ray (GCR) induced ionisation on cloud droplets in circumstances with relevance to Venus’ atmosphere. Charge is known to lower the critical supersaturation required for cloud droplets to form; slightly larger droplets are stable at lower saturation ratios if sufficiently charged. Condensation of gas directly onto ions is also potentially possible on Venus if the atmosphere is sufficiently supersaturated. GCRs and the secondary charged particles they produce are therefore anticipated to affect cloud droplet behaviour on Venus.</p><p>Experiments have been conducted using electrically isolated droplets, through levitation in a standing acoustic wave. The droplets are monitored with a high-magnification CCD camera to determine their evaporation rate and charge. The charge is measured both by the deflection in an electric field and by passing the droplet through a custom-built induction ring. A relationship between the evaporation rate and charge of the droplets is found to be consistent with theory, allowing droplet lifetime to be predicted for a given charge. Further experiments using sulphuric acid droplets in a carbon dioxide environment offer more direct relevance to the Venusian environment and cosmic ray enhancement due to solar energetic particles (SEPs) in space weather events will be simulated using a corona source.</p>

scholarly journals Anomalous Forbush effects from sources far from Sun center

2008 ◽  
Vol 4 (S257) ◽  
pp. 451-456
Author(s):  
E. Eroshenko ◽  
A. Belov ◽  
H. Mavromichalaki ◽  
V. Oleneva ◽  
A. Papaioannou ◽  
...  
Keyword(s):  
Solar Wind ◽  
Cosmic Ray ◽  
The Sun ◽  
Geomagnetic Disturbances ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
The Common ◽  
Solar Wind Parameters ◽  
Significant Disturbance ◽  
Forbush Effect

AbstractThe Forbush effects associated with far western and eastern powerful sources on the Sun that occurred on the background of unsettled and moderate interplanetary and geomagnetic disturbances have been studied by data from neutron monitor networks and relevant measurements of the solar wind parameters. These Forbush effects may be referred to a special sub-class of events, with the characteristics like the event in July 2005, and incorporated by the common conditions: absence of a significant disturbance in the Earth vicinity; absence of a strong geomagnetic storm; slow decrease of cosmic ray intensity during the main phase of the Forbush effect. General features and separate properties in behavior of density and anisotropy of 10 GV cosmic rays for this subclass are investigated.

Sign in / Sign up

Export Citation Format

Share Document