Navegando por Assunto "Molecular clouds"

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    Cosmic fertilization? Implantation of astrobiologically relevant cosmic rays in molecular clouds
    (Elsevier) Pilling, Sergio; Pazianotto, Maurício Tizziani
    This study investigates the implantation of astrobiologically relevant elements (e.g., carbon (C), oxygen (O), nitrogen (N), sulfur (S) and phosphorus (P)) into molecular clouds induced by cosmic rays. Using the Monte Carlo toolkit Geant4, we simulated the interaction of incoming high-energy protons and alpha particles with a mo- lecular clump characterized by a centrally concentrated density profile and a mass of approximately 30 M⊙. The results reveal a spatial gradient in implantation rates, with the highest rates occurring in the central regions due to increased target densities and reduced projectile energy. Protons (p) dominate the implantation process across all regions, followed by O, C, N, S, and P, with element-specific implantation efficiencies varying with distance from the clump center. This research identified regions inside the molecular cloud with distinct domains of atomic implantation enrichment with implications for astrobiology. The region at ∼1 AU exhibits the interesting atom implantation enrichment of the studied atoms, making it particularly significant for the formation of complex organic molecules. The findings highlight the importance of cosmic ray interactions in selectively enriching specific regions of molecular clouds with astrobiologically essential elements.
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    Energy Deposition by Cosmic Rays in the Molecular Cloud Using GEANT4 Code and Voyager I Data
    (IOP science) Pazianotto, Maurício Tizziani; Pilling, Sergio; Molina, Jose Manuel Quesada; Federico, Claudio Antonio
    Molecular clouds (MCs) are exposed to Galactic and extragalactic cosmic rays (CR) that trigger several physical and physicochemical changes, including gas and grain heating and molecular destruction and formation. Here we present a theoretical model describing the energy delivered by CRs, composed of protons, alphas, and electrons taken from Voyager I measurements, into a typical MC with 5400 M☉ (composed mainly of H with a density law of r −1.2) and size around 1 × 106 au. The calculation was performed employing the Monte Carlo toolkit GEANT4 to obtain the energy deposition per mass from several types of secondary particles (considering nuclear and hadron physics). The results indicate that incoming protons contribute to most of the energy delivered in the MC in all regions (maximum ∼230 MeV g−1 s −1 at outer regions of the cloud). Secondary electrons are the second most important component for energy deposition in almost all layers of the MC and can deliver an energy rate of ∼130 MeV g−1 s −1 in the outer region of the MC. Other cascade particles have their major energy delivery in the central and denser core of the MC. From a temperature model (considering CR data from Voyager I), we observed (i) a small bump in temperature at the distance of 3 × 103 –2 × 104 au from the center, (ii) a rapid temperature decrease (roughly 7 K) between the outer layer and the second most outer layer, and (iii) that, at a distance of 5 × 104 au (Av > 10), the gas temperature of the MC is below 15 K.