Solar and Heliospheric Modulation of Galactic Cosmic Rays

Heber, B.; Fichtner, H.; Scherer, K.

doi:10.1007/978-0-387-48341-2_7

Cited by 8 publications

(12 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…can not reproduce the cross-over of the modulation amplitude, i.e. the intensities are higher for low energy protons in an A > 0 than in an A < 0 solar magnetic epoch, while the opposite is the case for higher energies, which can be clearly seen in Figure 20 of Heber et al [2006].…”

Section: Comparison Of the Spectramentioning

confidence: 96%

On the importance of the local interstellar spectrum for the solar modulation parameter

Herbst¹,

Kopp²,

Heber³

et al. 2010

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[1] Cosmogenic Isotopes are produced in the Earth's atmosphere due to the interaction of galactic cosmic rays with nuclei of atmospheric atoms. Among others, the 10 Be concentration in ice cores depends on the galactic cosmic ray flux outside of the Earth's magnetosphere and provides therefore a unique tool to investigate the solar modulation over very long time periods. In this study we investigate the importance of different local interstellar proton spectra often used in literature obtained outside of the Earth's magnetosphere. In order to parameterize the heliospheric modulation we apply the forcefield solution using individual local interstellar proton spectrum (LIS) model dependent values. Thus among atmospheric and magnetospheric processes, the 10 Be concentration depends on an interplay of the different LIS and their modulation parameters. Since 10 Be measurements do not provide any spectral resolution, PAMELA data have been used for a comparison with the calculated spectra and to provide the model dependent modulation parameters during the solar minimum in July 2006. Within the limitation of the force-field solution and the freedom in parameter space, all LIS lead to a reasonable agreement with the data. Taking the LIS dependency of the modulation parameter into account, we derive linear equations to convert the individual between the different LIS. The conversions used here are then applied to a long-term reconstruction of derived from a record of the cosmogenic radionuclide 10 Be. By using the derived LIS conversions, we show that the occasionally observed negative values in the reconstruction of Steinhilber et al. (2008) vanish if another LIS model is used. In order to estimate other processes which alter this conclusion, the influence of the palaeo-magnetic field has been included. Thus, if all inner-heliospheric effects on the 10 Be flux would be known, this investigation would have the potential to rule out certain LIS.

show abstract

Section: Comparison Of the Spectramentioning

confidence: 96%

On the importance of the local interstellar spectrum for the solar modulation parameter

Herbst¹,

Kopp²,

Heber³

et al. 2010

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Broadly speaking, the stronger the solar activity the higher would be the deflection of interplanetary GCRs, resulting in a reduction of the GCR flux. This relationship can be often observed as an anticorrelation between neutron monitor counts (reflecting the GCR flux intensity at Earth) and the sunspot number (a standard measurement of solar activity) (Heber et al 2007). This modulation is however energy-dependent: the flux of low-energy GCRs is more affected than that of the high-energy GCRs.…”

Section: Radiation Environment and Dose Rate Variations In Transit Tomentioning

confidence: 99%

“…In general, solar modulation affects particles with different energies in different degrees, i.e., Φ has a stronger/weaker effect on GCR particles with lower/higher energies (Heber et al 2007). For any given species, a lower-energy ion contributes more to dose than does a higher-energy ion; we therefore expect that solar modulation has a more pronounced effect on dose than it does on integral fluxes.…”

Section: Estimates Of the Cruise Radiation Environment Under Differenmentioning

confidence: 99%

Variations of dose rate observed by MSL/RAD in transit to Mars

Guo

Zeitlin

Wimmer‐Schweingruber

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. To predict the cruise radiation environment related to future human missions to Mars, the correlation between solar modulation potential and the dose rate measured by the Radiation Assessment Detector (RAD) has been analyzed and empirical models have been employed to quantify this correlation. Methods. The instrument RAD, onboard Mars Science Laboratory's (MSL) rover Curiosity, measures a broad spectrum of energetic particles along with the radiation dose rate during the 253-day cruise phase as well as on the surface of Mars. With these first ever measurements inside a spacecraft from Earth to Mars, RAD observed the impulsive enhancement of dose rate during solar particle events as well as a gradual evolution of the galactic cosmic ray (GCR) induced radiation dose rate due to the modulation of the primary GCR flux by the solar magnetic field, which correlates with long-term solar activities and heliospheric rotation. Results. We analyzed the dependence of the dose rate measured by RAD on solar modulation potentials and estimated the dose rate and dose equivalent under different solar modulation conditions. These estimations help us to have approximate predictions of the cruise radiation environment, such as the accumulated dose equivalent associated with future human missions to Mars. Conclusions. The predicted dose equivalent rate during solar maximum conditions could be as low as one-fourth of the current RAD cruise measurement. However, future measurements during solar maximum and minimum periods are essential to validate our estimations.

show abstract

“…This is attributed to effects such as diffusion, convection, adiabatic deceleration as well as gradient and curvature drifts (see, e.g. Kallenrode, 2000;Heber et al, 2006). The theoretical basis for this approach is described by Fichtner (2001, section 2.3).…”

Section: Cosmic Ray Flux Outside the Magnetosphere As A Function Of Omentioning

confidence: 99%

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Grießmeier

Stadelmann

Grenfell

et al. 2009

Icarus

View full text Add to dashboard Cite

Previous studies have shown that extrasolar Earth-like planets in close-in habitable zones around M-stars are weakly protected against galactic cosmic rays (GCRs), leading to a strongly increased particle flux to the top of the planetary atmosphere. Two main effects were held responsible for the weak shielding of such an exoplanet: (a) For a close-in planet, the planetary magnetic moment is strongly reduced by tidal locking. Therefore, such a close-in extrasolar planet is not protected by an extended magnetosphere. (b) The small orbital distance of the planet exposes it to a much denser stellar wind than that prevailing at larger orbital distances. This dense stellar wind leads to additional compression of the magnetosphere, which can further reduce the shielding efficiency against GCRs. In this work, we analyse and compare the effect of (a) and (b), showing that the stellar wind variation with orbital distance has little influence on the cosmic ray shielding. Instead, the weak shielding of M star planets can be attributed to their small magnetic moment. We further analyse how the planetary mass and composition influence the planetary magnetic moment, and thus modify the cosmic ray shielding efficiency. We show that more massive planets are not necessarily better protected against galactic cosmic rays, but that the planetary bulk composition can play an important role.

show abstract

Solar and Heliospheric Modulation of Galactic Cosmic Rays

Cited by 8 publications

References 45 publications

On the importance of the local interstellar spectrum for the solar modulation parameter

On the importance of the local interstellar spectrum for the solar modulation parameter

Variations of dose rate observed by MSL/RAD in transit to Mars

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Contact Info

Product

Resources

About