Variations in the neutron intensity near the Earth’s surface modulate the functional state of the blood

Belisheva, N. K.; Kuzhevskij, B. M.; Sigaeva, E. A.; Panasyuk, M. I.; Zhirov, V. K.

doi:10.1134/s1607672906020104

Cited by 7 publications

(5 citation statements)

References 1 publication

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“…If parts of the cosmic-ray shower reach the planetary surface, one could expect that biological systems there can be strongly influenced and even damaged by this secondary radiation. This expectation is backed up by experimental evidence, which shows that during Ground Level Enhancements (extreme events where large numbers of secondary cosmic rays reach the Earth's surface) DNA lesions on the cellular level increase considerably Grießmeier et al, 2005;Belisheva et al, 2006;Dartnell, 2011;Belisheva et al, 2012, and references therein). In the case of Earth, muons contribute 75% of the equivalent dose rate at the surface (O'Brien et al, 1996).…”

Section: Surface Biological Dose Ratementioning

confidence: 97%

Galactic cosmic rays on extrasolar Earth-like planets

Grießmeier¹,

Tabataba‐Vakili²,

Stadelmann³

et al. 2015

A&A

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Context. Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields, especially in the case of planets more massive than Earth (super-Earths). Planetary magnetic fields, however, constitute one of the shielding layers that protect the planet against cosmic-ray particles. In particular, a weak magnetic field results in a high flux of Galactic cosmic rays that extends to the top of the planetary atmosphere. Aims. We wish to quantify the flux of Galactic cosmic rays to an exoplanetary atmosphere as a function of the particle energy and of the planetary magnetic moment. Methods. We numerically analyzed the propagation of Galactic cosmic-ray particles through planetary magnetospheres. We evaluated the efficiency of magnetospheric shielding as a function of the particle energy (in the range 16 MeV ≤ E ≤ 524 GeV) and as a function of the planetary magnetic field strength (in the range 0 M ⊕ ≤ M ≤ 10 M ⊕ ). Combined with the flux outside the planetary magnetosphere, this gives the cosmic-ray energy spectrum at the top of the planetary atmosphere as a function of the planetary magnetic moment. Results. We find that the particle flux to the planetary atmosphere can be increased by more than three orders of magnitude in the absence of a protecting magnetic field. For a weakly magnetized planet (M = 0.05 M ⊕ ), only particles with energies below 512 MeV are at least partially shielded. For a planet with a magnetic moment similar to that of Earth, this limit increases to to 32 GeV, whereas for a strongly magnetized planet (M = 10.0 M ⊕ ), partial shielding extends up to 200 GeV. Over the parameter range we studied, strong shielding does not occur for weakly magnetized planets. For a planet with a magnetic moment similar to that of Earth, particles with energies below 512 MeV are strongly shielded, and for strongly magnetized planets, this limit increases to 10 GeV. Conclusions. We find that magnetic shielding strongly controls the number of cosmic-ray particles reaching the planetary atmosphere. The implications of this increased particle flux are discussed in a companion article.

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Section: Surface Biological Dose Ratementioning

confidence: 97%

Galactic cosmic rays on extrasolar Earth-like planets

Grießmeier¹,

Tabataba‐Vakili²,

Stadelmann³

et al. 2015

A&A

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show abstract

“…This expectation is backed up by experimental evidence, which shows that during Ground Level Enhancements (extreme events where large numbers of secondary cosmic rays reach the Earth's surface) DNA lesions on the cellular level increase considerably (Belisheva et al 2005;Grießmeier et al 2005;Belisheva et al 2006Belisheva et al , 2012Dartnell 2011, and references therein). In the case of Earth, muons contribute 75% of the equivalent dose rate at the surface (O'Brien et al 1996).…”

Section: Surface Biological Dose Ratementioning

confidence: 98%

Galactic cosmic rays on extrasolar Earth-like planets

Grießmeier

Vakili

Stadelmann

et al. 2016

A&A

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Context. Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields. As described in the companion article (Paper I), a weak magnetic field results in a high flux of galactic cosmic rays to the top of the planetary atmosphere. Aims. We investigate effects that may result from a high flux of galactic cosmic rays both throughout the atmosphere and at the planetary surface. Methods. Using an air shower approach, we calculate how the atmospheric chemistry and temperature change under the influence of galactic cosmic rays for Earth-like (N 2 -O 2 dominated) atmospheres. We evaluate the production and destruction rate of atmospheric biosignature molecules. We derive planetary emission and transmission spectra to study the influence of galactic cosmic rays on biosignature detectability. We then calculate the resulting surface UV flux, the surface particle flux, and the associated equivalent biological dose rates. Results. We find that up to 20% of stratospheric ozone is destroyed by cosmic-ray protons. The effect on the planetary spectra, however, is negligible. The reduction of the planetary ozone layer leads to an increase in the weighted surface UV flux by two orders of magnitude under stellar UV flare conditions. The resulting biological effective dose rate is, however, too low to strongly affect surface life. We also examine the surface particle flux: For a planet with a terrestrial atmosphere (with a surface pressure of 1033 hPa), a reduction of the magnetic shielding efficiency can increase the biological radiation dose rate by a factor of two, which is non-critical for biological systems. For a planet with a weaker atmosphere (with a surface pressure of 97.8 hPa), the planetary magnetic field has a much stronger influence on the biological radiation dose, changing it by up to two orders of magnitude. Conclusions. For a planet with an Earth-like atmospheric pressure, weak or absent magnetospheric shielding against galactic cosmic rays has little effect on the planet. It has a modest effect on atmospheric ozone, a weak effect on the atmospheric spectra, and a noncritical effect on biological dose rates. For planets with a thin atmosphere, however, magnetospheric shielding controls the surface radiation dose and can prevent it from increasing to several hundred times the background level.

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“…Published data show that the thermal neutron radiation capture cross-section for protium is one-fourth of the total scattering cross-section [7]. The biological effect of ultraweak thermal neutron fluxes was detected in various organisms [1,6,11]. Corpuscular radiation of this type may serve as one of the major intermediates in the response of living organisms to astrogeophysical events.…”

Section: Bulletin Of Experimental Biology and Medicine Vol 143 Nomentioning

confidence: 99%

“…Moreover, it increases by many times during solar flares. Previous studies revealed the existence of strong biological responses to ultraweak fluxes of thermal neutrons (V. V. Lednev et al) [1,6,11]. These data suggest that thermal neutrons has a function of messengers, which allows the perception of astrogeophysical events by living organisms.…”

mentioning

confidence: 90%

Abnormal changes in the density of thermal neutron flux in biocenoses near the earth surface

et al. 2007

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We revealed an increase in the density of thermal neutron flux in forest biocenoses, which was not associated with astrogeophysical events. The maximum spike of this parameter in the biocenosis reached 10,000 n/(sec x m2). Diurnal pattern of the density of thermal neutron flux depended only on the type of biocenosis. The effects of biomodulation of corpuscular radiation for balneology are discussed.

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Variations in the neutron intensity near the Earth’s surface modulate the functional state of the blood

Cited by 7 publications

References 1 publication

Galactic cosmic rays on extrasolar Earth-like planets

Galactic cosmic rays on extrasolar Earth-like planets

Galactic cosmic rays on extrasolar Earth-like planets

Abnormal changes in the density of thermal neutron flux in biocenoses near the earth surface

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