scholarly journals On the possibility of galactic cosmic ray-induced radiolysis-powered life in subsurface environments in the Universe

2016 ◽  
Vol 13 (123) ◽  
pp. 20160459 ◽  
Author(s):  
Dimitra Atri
Keyword(s):  
South African ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Solar Origin ◽  
Secondary Particles ◽  
Available Energy ◽  
Subsurface Environments ◽  
Terrestrial Life ◽  
Galactic Cosmic Ray ◽  
The Universe

Photosynthesis is a mechanism developed by terrestrial life to utilize the energy from photons of solar origin for biological use. Subsurface regions are isolated from the photosphere, and consequently are incapable of utilizing this energy. This opens up the opportunity for life to evolve alternative mechanisms for harvesting available energy. Bacterium Candidatus Desulforudis audaxviator , found 2.8 km deep in a South African mine, harvests energy from radiolysis, induced by particles emitted from radioactive U, Th and K present in surrounding rock. Another radiation source in the subsurface environments is secondary particles generated by galactic cosmic rays (GCRs). Using Monte Carlo simulations, it is shown that it is a steady source of energy comparable to that produced by radioactive substances, and the possibility of a slow metabolizing life flourishing on it cannot be ruled out. Two mechanisms are proposed through which GCR-induced secondary particles can be utilized for biological use in subsurface environments: (i) GCRs injecting energy in the environment through particle-induced radiolysis and (ii) organic synthesis from GCR secondaries interacting with the medium. Laboratory experiments to test these hypotheses are also proposed. Implications of these mechanisms on finding life in the Solar System and elsewhere in the Universe are discussed.

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 Structure of the Power Spectral Density of Galactic Cosmic Ray Variation during 1953-2016

2017 ◽  
Vol 13 (S335) ◽  
pp. 82-86
Author(s):  
Pauli Väisänen ◽  
Ilya Usoskin ◽  
Kalevi Mursula
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Period Range ◽  
Power Spectral ◽  
Hourly Data ◽  
Spectral Peaks ◽  
Two Peaks ◽  
Galactic Cosmic Ray

AbstractFluxes of galactic cosmic rays (GCR) observed at 1 AU are modulated inside the heliosphere at different time scales. Here we study the properties of the power spectral density (PSD) of galactic cosmic ray variability using hourly data from 31 neutron monitors (NM) from 1953 to 2016. We pay particular attention to the reliability of the used datasets and methods. We present the overall PSD and discuss different parts of the spectrum and the related periodicities. We find significant spectral peaks at the periods of 11 years, 1.75 years, 155 days, 27 days and 24 hours and the harmonics of the latter two peaks. We calculate a power law slope of −1.79 ± 0.13 for the period range between 50 and 130 hours and a slope of −1.34 ± 0.17 for the period range between 40 days and 3.4 years (1000 − 30000 h).

EFFECTS OF FLIGHT ROUTE VARIATION AND GREAT-CIRCLE APPROXIMATION ON AVIATION DOSE ASSESSMENT FOR POPULAR FLIGHTS FROM TAIWAN

2018 ◽  
Vol 184 (1) ◽  
pp. 79-89 ◽  
Author(s):  
Zi-Yi Yang ◽  
Rong-Jiun Sheu
Keyword(s):  
Cosmic Ray ◽  
Mean Value ◽  
Great Circle ◽  
Dose Assessment ◽  
Tracking Data ◽  
Secondary Particles ◽  
The Mean ◽  
Flight Route ◽  
Airline Crews ◽  
Galactic Cosmic Ray

Abstract Galactic cosmic-ray-induced secondary particles in the atmosphere constitute an important source of radiation exposure to airline crews and passengers. In this study, a systematic dose assessment was conducted for 11 popular flights from Taiwan, with an emphasis on the effects of flight route variation and assumption. The case studies covered a broad range of commercial flights departing from Taipei, from a domestic flight of <1 h to a long-haul international flight of more than 14 h. For each route under study, information on 100 actual flight routes was retrieved from flight tracking data collected from June to September 2017, and the information was analyzed using a self-developed program called the ‘NTHU Flight Dose Calculator’. The resulting distribution of route doses provided not only the mean value and associated standard deviation but also information on the characteristics of aviation dose assessment and management. Furthermore, compared with actual flight routes, the dose differences introduced by great-circle approximation were evaluated, and the effects of solar activity on the dose assessment of these flights were reported.

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;

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

&lt;p&gt;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&amp;#8217; 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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

Galactic Cosmic Ray Anisotropies in the Energy Range 1011 – 1014eV.

1986 ◽  
Vol 6 (4) ◽  
pp. 425-436 ◽  
Author(s):  
R.M. Jacklyn
Keyword(s):  
Energy Range ◽  
Analytical Techniques ◽  
Cosmic Ray ◽  
Air Showers ◽  
Solar Origin ◽  
Particle Intensity ◽  
Galactic Cosmic Ray ◽  
Descriptive Models

AbstractA review is presented of the evidence for anisotropies of galactic origin in the charged cosmic ray particle intensity at median primary energies of detection in the range 1011 – 1014eV. It concerns the period from 1958, when the first substantial long-term observations at energies of solar and sidereal modulation near 1011eV commenced underground, until 1984, by which time results were available from a number of years of accurate observations with detectors of small air showers at energies near 1014eV, too high for complicating effects of solar origin to be present. There is evidence for the existence of both unidirectional and bidirectional galactic anisotropies over the whole energy range. Tentative descriptive models are discussed in relation to advances both in solar and sidereal analytical techniques and in the ability of experimenters to account for and exploit the modulating influence of the heliomagnetosphere at the lower energies of detection.

scholarly journals Charting nearby stellar systems: The intensity of Galactic cosmic rays for a sample of solar-type stars

2021 ◽  
Author(s):  
Donna Rodgers-Lee ◽  
Aline Vidotto ◽  
Amanda Mesquita
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Stellar Winds ◽  
Habitable Zone ◽  
Chemical Modelling ◽  
Solar Type ◽  
Prebiotic Molecules ◽  
Exoplanetary Atmospheres ◽  
Galactic Cosmic Ray

&lt;p&gt;Galactic cosmic rays are important for exoplanetary atmospheres. They can contribute to the formation of hazes, prebiotic molecules and atmospheric electrical circuits. A number of so-called fingerprint ions, such as oxonium, have been identified from chemical modelling which are thought to be signatures of ionisation by energetic particles, such as Galactic cosmic rays. These fingerprint ions may be observed in exoplanetary atmospheres with upcoming JWST observations.&lt;/p&gt; &lt;p&gt;I will discuss our recent results that model the propagation of Galactic cosmic rays through the stellar winds of a number of nearby solar-type stars. Our sample comprises of 5 well-observed solar-type stars that we have constructed well-constrained stellar wind models for. This allows us to calculate the transport of Galactic cosmic rays through these systems. I will present our results of the Galactic cosmic ray fluxes that reach (a) the habitable zone and (b) the location of known exoplanets. The systems show a variety of behaviour and I will discuss the most promising systems for upcoming JWST observations.&amp;#160;&lt;/p&gt;

scholarly journals Fine and Hyperfine Structure in the Spectrum of Secular Variations of Atmospheric 14C

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 704-718 ◽  
Author(s):  
Paul E Damon ◽  
Songlin Cheng ◽  
Timothy W Linick
Keyword(s):  
Cosmic Rays ◽  
Hyperfine Structure ◽  
Ice Cores ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Solar Cosmic Rays ◽  
Secular Variations ◽  
Galactic Cosmic Ray ◽  
Long Term Trend

The coarse structure of the 14C spectrum consists of a secular trend curve that may be closely fit by a sinusoidal curve with period ca 11,000 yr and half amplitude ±51. This long-term trend is the result of changes in the earth's geomagnetic dipole moment. Consequently, it modulates solar components of the 14C spectrum but does not appear to modulate a component of the spectrum of ca 2300-yr period. The ca 2300-yr period is of uncertain origin but may be due to changes in climate because it also appears in the δ18O spectrum of ice cores. This component strongly modulates the well-known ca 200-yr period of the spectrum's fine structure. The hyperfine structure consists of two components that fluctuate with the 11-yr solar cycle. One component results from solar-wind modulation of the galactic cosmic rays and has a half-amplitude of ca ±1.5. The other component is the result of 14C production by solar cosmic rays that arrive more randomly but rise and fall with the 11-yr cycle and appear to dominate the fluctuation of the galactic cosmic-ray-produced component by a factor of two.

scholarly journals Possible effects on Earth's climate due to reduced atmospheric ionization by GCR during Forbush Decreases

2016 ◽  
Vol 12 (S328) ◽  
pp. 298-300
Author(s):  
Williamary Portugal ◽  
Ezequiel Echer ◽  
Mariza Pereira de Souza Echer ◽  
Alessandra Abe Pacini
Keyword(s):  
Surface Temperature ◽  
Chemical Properties ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Forbush Decreases ◽  
First Results ◽  
Earth’S Climate ◽  
Galactic Cosmic Ray ◽  
Cosmic Ray Flux ◽  
Atmospheric Ionization

AbstractThis work presents the first results of a study about possible effects on the surface temperature during short periods of lower fluxes of Galactic Cosmic Rays at Earth, called Forbush Decreases. There is a hypothesis that the Galactic Cosmic Ray flux decreases cause changes on the physical-chemical properties of the atmosphere. We have conducted a study to investigate these possible effects on several latitudinal regions, around the ten strongest FDs occurred from 1987 to 2015. We have found a possible increase on the surface temperature at middle and high latitudes during the occurence of these events.

scholarly journals On periodicities in long term climatic variations near 68° N, 30° E

2007 ◽  
Vol 13 ◽  
pp. 25-29 ◽  
Author(s):  
E. A. Kasatkina ◽  
O. I. Shumilov ◽  
M. Krapiec
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Solar Radiation ◽  
Solar Magnetic Field ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Solar Cycles ◽  
Galactic Cosmic Ray

Abstract. It is generally believed that the low-frequency variability of climatic parameters seems to be connected to solar cycles. The principal periodicities are: 11-year (Schwabe), 22-year (Hale), 33-year (Bruckner) and 80–100-year (Gleissberg) cycles. The main heliophysical factors acting on climate, the biosphere and the atmosphere are solar irradiance, the intensity of solar and galactic cosmic rays (relativistic charged particles with energies >500 MeV) changing the cloud cover of the atmosphere, and UV-B-radiation. The 11-year and 80–90-year solar cycles are apparent in solar radiation and galactic cosmic ray trends. At the same time the bidecadal Hale cycle, related to a reversal of the main solar magnetic field direction is practically absent in either solar radiation or galactic cosmic ray variations. Besides, nobody can identify any physical mechanisms by which a reversal in the solar magnetic field direction could influence climate. However, the 22-year cycle has been identified in rather many regional climatic (droughts, rainfall, tree growth near 68° N, 30° E) and temperature records all over the world. We discuss here three possible cause of the bidecadal periodicity in climatic records, one of which is associated with a variation of stardust flux inside the Solar System. The most recent observations by the DUST experiment on board the Ulysses spacecraft have shown that the solar magnetic field lost its protective power during the last change of its polarity (the most recent solar maximum), so that the stardust level inside of the Solar System has been enhanced by a factor of three. It is possible that the periodic increases of stardust in the Solar System may influence the amount of extraterrestrial material that falls to the Earth and consequently act on the Earth's atmosphere and climate through alteration of atmospheric transparency and albedo. This material (interstellar dust and/or cometary matter) may also provide nucleation sites and thereby influence precipitation.

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