Comment on “Solar influences on cosmic rays and cloud formation: A reassessment” by Bomin Sun and Raymond S. Bradley

2004 ◽  
Vol 109 (D14) ◽  
Author(s):  
Nigel Marsh
Keyword(s):  
Cosmic Rays ◽  
Cloud Formation

Modelling the influence of high-energy radiation on the atmospheric composition of the hot Jupiter HD 189733b

2021 ◽  
Author(s):  
Patrick Barth ◽  
Christiane Helling ◽  
Eva E. Stüeken ◽  
Vincent Bourrier ◽  
Nathan Mayne ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Atmospheric Composition ◽  
Cloud Formation ◽  
Fine Grid ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Hot Jupiter

<p>Hot Jupiters provide valuable natural laboratories for studying potential contributions of high-energy radiation to prebiotic synthesis in the atmospheres of exoplanets. HD 189733b, a hot Jupiter orbiting a K star, is one of the most studied and best observed exoplanets. We combine XUV observations and 3D climate simulations to model the atmospheric composition and kinetic chemistry with the STAND2019 network. We show how XUV radiation, cosmic rays (CR), and stellar energetic particles (SEP) influence the chemistry of the atmosphere. We explore the effect that the change in the XUV radiation has over time, and we identify key atmospheric signatures of an XUV, CR, and SEP influx. 3D simulations of HD 189733b's atmosphere with the 3D Met Office Unified Model provide a fine grid of pressure-temperature profiles, consistently taking into account kinetic cloud formation. We apply <em>HST</em> and <em>XMM-Newton/Swift</em> observations obtained by the MOVES programmewhich provide combined X-ray and ultraviolet (XUV) spectra of the host star HD 189733 at 4 different points in time. We find that the differences in the radiation field between the irradiated dayside and the shadowed nightside lead to stronger changes in the chemical abundances than the variability of the host star's XUV emission. We identify ammonium (NH<sub>4</sub><sup>+</sup>) and oxonium (H<sub>3</sub>O<sup>+</sup>) as fingerprint ions for the ionization of the atmosphere by both galactic cosmic rays and stellar particles. All considered types of high-energy radiation have an enhancing effect on the abundance of key organic molecules such as hydrogen cyanide (HCN), formaldehyde (CH<sub>2</sub>O), and ethylene (C<sub>2</sub>H<sub>4</sub>). The latter two are intermediates in the production pathway of the amino acid glycine (C<sub>2</sub>H<sub>5</sub>NO<sub>2</sub>) and abundant enough to be potentially detectable by <em>JWST</em>. Ultimately, we show that high energy processes potentially play an important role in prebiotic chemistry.</p><p>P Barth et al., MOVES IV. Modelling the influence of stellar XUV-flux, cosmic rays, and stellar energetic particles on the atmospheric composition of the hot Jupiter HD 189733b, <em>Monthly Notices of the Royal Astronomical Society</em>, in press, DOI:10.1093/mnras/staa3989</p>

scholarly journals Rayleigh Taylor Instabilities in the Interstellar Medium

1981 ◽  
Vol 94 ◽  
pp. 253-254
Author(s):  
Marc Lachièze-Rey
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Interstellar Medium ◽  
Equilibrium Model ◽  
Galactic Evolution ◽  
Cloud Formation ◽  
Halo Formation ◽  
Evolution Time ◽  
The Galaxy

Parker (1966, 1969) proposed that the interstellar medium could be subjected to instabilities, able to destroy its structure in a time shorter than the galactic evolution time. He emitted the idea that this phenomenon could lead to halo formation, escape of magnetic field and cosmic rays from the galaxy, via some sort of interstellar “bubbles”, and also to cloud formation. He showed then that if the interstellar medium was well represented by a simple horizontal stratified equilibrium model, perturbations would effectively grow and destroy the structure.

scholarly journals The evidence for and against astronomical impacts on climate change and mass extinctions: a review

2009 ◽  
Vol 8 (3) ◽  
pp. 213-219 ◽  
Author(s):  
C.A.L. Bailer-Jones
Keyword(s):  
Climate Change ◽  
Cosmic Rays ◽  
Plate Tectonics ◽  
Cloud Formation ◽  
Causal Connection ◽  
The Sun ◽  
Mass Extinctions ◽  
Sea Level Changes ◽  
Impact Cratering ◽  
The Past

AbstractNumerous studies over the past 30 years have suggested there is a causal connection between the motion of the Sun through the Galaxy and terrestrial mass extinctions or climate change. Proposed mechanisms include comet impacts (via perturbation of the Oort cloud), cosmic rays and supernovae, the effects of which are modulated by the passage of the Sun through the Galactic midplane or spiral arms. Supposed periodicities in the fossil record, impact cratering dates or climate proxies over the Phanerozoic (past 545 Myr) are frequently cited as evidence in support of these hypotheses. This remains a controversial subject, with many refutations and replies having been published. Here I review both the mechanisms and the evidence for and against the relevance of astronomical phenomena to climate change and evolution. This necessarily includes a critical assessment of time series analysis techniques and hypothesis testing. Some of the studies have suffered from flaws in methodology, in particular drawing incorrect conclusions based on ruling out a null hypothesis. I conclude that there is little evidence for intrinsic periodicities in biodiversity, impact cratering or climate on timescales of tens to hundreds of Myr. Although this does not rule out the mechanisms, the numerous assumptions and uncertainties involved in the interpretation of the geological data and in particular in the astronomical mechanisms suggest that Galactic midplane and spiral arm crossings have little impact on biological or climate variation above background level. Non-periodic impacts and terrestrial mechanisms (volcanism, plate tectonics, sea level changes), possibly occurring simultaneously, remain likely causes of many environmental catastrophes. Internal dynamics of the biosphere may also play a role. In contrast, there is little evidence supporting the idea that cosmic rays have a significant influence on climate through cloud formation. It seems likely that more than one mechanism has contributed to biodiversity variations over the past half Gyr.

Shielding Space Explorers From Cosmic Rays

Space Weather ◽  
2005 ◽  
Vol 3 (8) ◽  
pp. n/a-n/a ◽  
Author(s):  
Eugene N. Parker
Keyword(s):  
Cosmic Rays
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