The Atmospheric Radiation Interaction Simulator (AtRIS): Description and Validation

Banjac, Saša; Herbst, K.; Heber, Bernd

doi:10.1029/2018ja026042

Cited by 36 publications

(52 citation statements)

References 56 publications

(87 reference statements)

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“…scaled to Prox Cen b (based onHerbst et al, 2019) GLE05 (as measured at Earth in February 1956) Upper panel: Observed GLE event spectrum of GLE05 (blue) compared to the scaled event spectrum at Prox Cen b (red) including the corresponding error band (red shaded region) and cutoff energy on top of the atmosphere (TOA) (grey dashed). Lower panel: Corresponding event-induced atmospheric ion pair production rates at Earth (blue) and at Prox Cen b (red).…”

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confidence: 99%

Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies

Scheucher

Herbst

Schmidt

et al. 2020

ApJ

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Due to its Earth-like minimum mass of 1.27 M E and its close proximity to our Solar system, Proxima Centauri b is one of the most interesting exoplanets for habitability studies. Its host star, Proxima Centauri, is however a strongly flaring star, which is expected to provide a very hostile environment for potentially habitable planets. We perform a habitability study of Proxima Centauri b assuming an Earth-like atmosphere under high stellar particle bombardment, with a focus on spectral transmission features. We employ our extensive model suite calculating energy spectra of stellar particles, their journey through the planetary magnetosphere, ionosphere, and atmosphere, ultimately providing planetary climate and spectral characteristics, as outlined in Herbst et al. (2019b). Our results suggest that together with the incident stellar energy flux, high particle influxes can lead to efficient heating of the planet well into temperate climates, by limiting CH 4 amounts, which would otherwise run into anti-greenhouse for such planets around M-stars. We identify some key spectral features relevant for future spectral observations: First, NO 2 becomes the major absorber in the visible, which greatly impacts the Rayleigh slope. Second, H 2 O features can be masked by CH 4 (near infra-red) and CO 2 (mid to far infra-red), making them non-detectable in transmission. Third, O 3 is destroyed and instead HNO 3 features become clearly visible in the mid to far infra-red. Lastly, assuming a few percent of CO 2 in the atmosphere, CO 2 absorption at 5.3 µm becomes significant (for flare and non-flare cases), strongly overlapping with a flare related NO feature in Earth's atmosphere.

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confidence: 99%

Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies

Scheucher

Herbst

Schmidt

et al. 2020

ApJ

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“…Here we provided updated altitude-dependent Venusian radiation dose profiles based on the newly developed full 3D Monte Carlo simulation code AtRIS (Banjac et al 2019b). We used the most recent numerical physics models (Geant4 10.5, FTFP_BERT_HP) as well as the primary GCR spectra of hydrogen (Z=1) to nickel (Z=28) from the CREME2009 model (see, e.g., Tylka et al 1997) with energies between 1 MeV and 10 TeV.…”

Section: Discussionmentioning

confidence: 99%

“…The main features of AtRIS are i) the planet specification format (PSF), ii) the atmospheric response matrices (ARMs), which quantify the relationship between primary energy and altitude-dependent ionization, absorbed dose rate and dose equivalent, and iii) the spectrum-folding procedure used to calculate net quantities such as the electron-ion pair production rate by implementing a convolution of a spectrum and the ARM. A detailed description of the main features is given in Banjac et al (2019b). At this point, AtRIS has successfully been validated for the terrestrial, the Martian, and the Venusian atmosphere (see Banjac et al 2019b,a;Guo et al 2019;Herbst et al 2019a, respectively).…”

Section: Atmospheric Radiation Interaction Simulator (Atris)mentioning

confidence: 99%

“…We like to point out that the shape and size of different phantoms can vary. Different shapes, however, account for different geometric factors: g = π · 2a 2 for a slab detector, g = π · 2r 2 for a disk detector, and a spherical detector, for example, a planetary atmospheric layer, has a geometrical factor of π · 4πr 2 (see, e.g., Banjac et al 2019a). By placing phantoms of different sizes and shapes within the same radiation field, the number of particles that can penetrate the phantom and thereby deposit energy within, therefore decreases as the square of the phantom radius.…”

Section: Atmospheric Radiation Interaction Simulator (Atris)mentioning

confidence: 99%

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Revisiting the cosmic-ray induced Venusian radiation dose in the context of habitability

Herbst

Banjac

Atri³

et al. 2019

A&A

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Context. Cosmic rays (CRs), which constantly bombard planetary magnetic fields and atmospheres, are the primary driver of atmospheric spallation processes. The higher the energy of these particles, the deeper they penetrate the planetary atmosphere, and the more likely interactions become with the ambient atmospheric material and the evolution of secondary particle showers. Aims. As recently discussed in the literature, CRs are the dominant driver of the Venusian atmospheric ionization and the induced radiation dose below ∼100 km. In this study, we model the atmospherically absorbed dose and the dose equivalent to the effect of cosmic rays in the context of Venusian habitability. Methods. The Atmospheric Radiation Interaction Simulator (AtRIS) was used to model the altitude-dependent Venusian absorbed dose and the Venusian dose equivalent. For the first time, we modeled the dose rates for different shape-, size-, and composition-mimicking detectors (phantoms): a CO 2 -based phantom, a water-based microbial cell, and a phantom mimicking human tissue. Results. Based on our new model approach, we give a reliable estimate of the altitude-dependent Venusian radiation dose in water-based microorganisms here for the first time. These microorganisms are representative of known terrestrial life. We also present a detailed analysis of the influence of the strongest ground-level enhancements measured at the Earth's surface, and of the impact of two historic extreme solar events on the Venusian radiation dose. Our study shows that because a phantom based on Venusian air was used, and because furthermore, the quality factors of different radiation types were not taken into account, previous model efforts have underestimated the radiation hazard for any putative Venusian cloud-based life by up to a factor of five. However, because we furthermore show that even the strongest events would not have had a hazardous effect on putative microorganisms within the potentially habitable zone (51 km -62 km), these differences may play only a minor role.

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“…The simulation code takes care to retain information about all energy losses that these particles suffer. Ultimately, one gets a response matrix of the atmosphere, which describes how different primary particles distribute their energy in the form of ionization throughout the atmosphere (see Banjac et al, , Figure therein). Still, in order to quantitatively compare the radiological conditions of different atmospheres, we need to investigate all the individual contributions to the net ionization.…”

Section: Introductionmentioning

confidence: 99%

On‐the‐Fly Calculation of Absorbed and Equivalent Atmospheric Radiation Dose in A Water Phantom with the Atmospheric Radiation Interaction Simulator (AtRIS)

et al. 2019

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Computation of the ionization and radiation dose in arbitrary (exo‐) planetary atmospheres due to energetic particles is recently becoming more important due to several reasons that are either correlated with the detection of trace gases for life on exoplanets or with computing dose rates at arbitrary altitudes in the Earth atmosphere. We previously presented Atmospheric Radiation Interaction Simulator, a new Geant4‐based code tailored specifically to enable parametric studies of radiation propagation through exoplanetary atmospheres (Banjac et al., 2019 https://doi.org/10.1029/2018JA026042). Therein, the calculation of ion‐electron pair production rates, which are a mandatory input for chemical and atmospheric modeling, has been presented and validated against Earth measurements and also other, similar, but solar‐system‐specific Geant4‐based codes (PLANETOCOSMICS). In addition to providing input for atmospheric modeling of exoplanets, with AtRIS we aim to directly characterize the habitability by calculating the absorbed dose. In this technical validation study, after showing a detailed analysis of the secondary particles contributing to the atmospheric radiation, we describe a feature of the code which makes direct parametric studies of the interrelation of incident radiation and the resulting absorbed dose throughout the atmosphere possible. In a validation case study configured using an atmospheric model obtained with NRLMSISE‐00 and a primary proton and helium GCR flux calculated using a recent improvement of the force‐field approach, we have compared simulation results with measurements obtained with the Flight Radiation Environment Detector (FRED). We show that Atmospheric Radiation Interaction Simulator (AtRIS) can reproduce the measured dose rate dependence on altitude.

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The Atmospheric Radiation Interaction Simulator (AtRIS): Description and Validation

Cited by 36 publications

References 56 publications

Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies

Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies

Revisiting the cosmic-ray induced Venusian radiation dose in the context of habitability

On‐the‐Fly Calculation of Absorbed and Equivalent Atmospheric Radiation Dose in A Water Phantom with the Atmospheric Radiation Interaction Simulator (AtRIS)

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