Related papers: Radiative processes as diagnostics of cometary atm…
Clouds are ubiquitous\, -- \,they arise for every solar system planet that possesses an atmosphere and have also been suggested as a leading mechanism for obscuring spectral features in exoplanet observations. As exoplanet observations…
The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…
The upper atmospheres of Mars and Titan, as well as those on many other planetary bodies, exhibit significant density variations vs. altitude that are interpreted as gravity waves. Such data is then used to extract vertical temperature…
The first computational model of solid-phase chemistry in cometary nuclear ices is presented. An astrochemical kinetics model, MAGICKAL, is adapted to trace the chemical evolution in multiple layers of cometary ice, over a representative…
All cometary nuclei that formed in the early Solar System incorporated radionuclides and therefore were subject to internal radiogenic heating. Previous work predicts that if comets have a pebble-pile structure internal temperature build-up…
In situ research on cometary chemistry began when measurements from the Giotto mission at comet 1P/Halley revealed the presence of complex organics in the coma. New telescopes and space missions have provided detailed remote and in situ…
Advancements in our understanding of exoplanetary atmospheres, from massive gas giants down to rocky worlds, depend on the constructive challenges between observations and models. We are now on a clear trajectory for improvements in…
Radio observations from decimetric to submillimetric wavelengths are now a basic tool for the investigation of comets. Spectroscopic observations allow us i) to monitor the gas production rate of the comets, by directly observing the water…
Context: Remote light scattering and thermal infrared observations provide clues about the physical properties of cometary and interplanetary dust particles. Identifying these properties will lead to a better understanding of the formation…
We present a model of cometary dust capable of simulating the dynamics within the first few tens of km of the comet surface. Recent measurements by the GIADA and COSIMA instruments on Rosetta show that the nucleus emits fluffy dust…
We summarize the collective knowledge of physical and surface properties of comet nuclei, focusing on those that are obtained from remote observations. We now have measurements or constraints on effective radius for over 200 comets,…
The chemical composition of comets is frequently assumed to be directly provided by the observations of the abundances of volatile molecules in the coma. The present work aims to determine the relationship between the chemical composition…
Recent results, the present status and the perspectives of high energy gamma-ray astronomy are described. Since the satellite observations by the Compton Gamma Ray Observatory and its precursor missions have been reviewed extensively,…
We are now on a clear trajectory for improvements in exoplanet observations that will revolutionize our ability to characterize their atmospheric structure, composition, and circulation, from gas giants to rocky planets. However, exoplanet…
Most of the ordinary matter in the local Universe has not been converted into stars but resides in a largely unexplored diffuse, hot, X-ray emitting plasma. It pervades the gravitational potentials of massive galaxies, groups and clusters…
Remote and in-situ observations of cometary gases have revealed the presence of a wealth of complex organic molecules, including carbon chains, alcohols, imines and the amino acid glycine. Such chemical complexity in cometary material…
The atmospheres of exoplanets reveal all their properties beyond mass, radius, and orbit. Based on bulk densities, we know that exoplanets larger than 1.5 Earth radii must have gaseous envelopes, hence atmospheres. We discuss contemporary…
Characterizing temperate exoplanet atmospheres remains challenging due to their small size and low temperatures. Recent JWST observations provide valuable data, but their interpretation has led to diverging conclusions. Complementary…
Radiative processes play a pivotal role in shaping the thermal and chemical states of gas across diverse astrophysical environments, from the interstellar medium (ISM) to the intergalactic medium. We present a hybrid cooling model for…
Far ultraviolet observations of comets yield information about the energetic processes that dissociate the sublimated gases from their primitive surfaces. Understanding which emission processes are dominant, their effects on the observed…