29 citations · 217 across the 22 of their papers we have counts for
22 papers
The Emergence of Prebiotic Chemistry in the ISM
Izaskun Jimenez-Serra, Giuliana Cosentino, Francisco Montenegro-Montes +22
Contrary to popular belief, the interstellar medium (ISM) is not empty; it is filled with atoms, dust particles, and molecules. Some of these molecules may have been the very build…
Redistribution of ices between grain populations in protostellar envelopes. Only the coldest grains get ices
Juris Kalvāns
Context. Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of i…
Effects of grain temperature distribution on organic protostellar envelope chemistry
Juris Kalvans, Juris Freimanis
Context. Dust grains in circumstellar envelopes are likely to have a spread-out temperature distribution. Aims. To investigate how trends in temperature distribution between small…
A multigrain-multilayer astrochemical model with variable desorption energy for surface species
Juris Kalvāns, Aija Kalniņa, Kristaps Veitners
Context. Interstellar surface chemistry is a complex process that occurs in icy layers accumulated onto grains of different sizes. Efficiency of surface processes often depends on…
Temperature Spectra of Interstellar Dust Grains Heated by Cosmic Rays. III. Mixed Composition Grains
Juris Kalvans, Juris Roberts Kalnin
Icy grains in the interstellar medium and star-formation regions consist of a variety of materials. Such composite grains interact differently with cosmic-ray (CR) particles compar…
Icy molecule desorption in interstellar grain collisions
Juris Kalvāns, Kedron Silsbee
Observations of gaseous complex organic molecules (COMs) in cold starless and prestellar cloud cores require efficient desorption of the COMs and their parent species from icy mant…
The connection between warm carbon chain chemistry and interstellar irradiation of star-forming cores
Juris Kalvans
Some observations of warm carbon chain chemistry (WCCC) cores indicate that they are often located near the edges of molecular clouds. This finding may suggest that WCCC is promote…
Evaporative cooling of icy interstellar grains II. Key parameters
Juris Kalvāns, Juris Roberts Kalnin
Context. Evaporative (sublimation) cooling of icy interstellar grains occurs when the grains have been suddenly heated by a cosmic-ray (CR) particle or other process. It results in…
Evaporative cooling of icy interstellar grains. I. Basic characterization
Juris Kalvans, Juris Roberts Kalnin
Context. While radiative cooling of interstellar grains is a well-known process, little detail is known about the cooling of grains with an icy mantle that contains volatile adsorb…
Chemical significance of different temperature regimes for cosmic-ray-induced heating of whole interstellar grains
Juris Kalvans, Juris Roberts Kalnin
Cosmic-ray-induced whole-grain heating induces evaporation and other processes that affect the chemistry of interstellar clouds. With recent data on grain heating frequencies as an…
Temperature spectra of interstellar dust grains heated by cosmic-rays II: dark cloud cores
Juris Kalvāns
Cosmic-ray (CR) induced heating of whole interstellar grains is an important desorption mechanism for grain surface molecules in interstellar molecular clouds. This study aims to p…
The efficiency of photodissociation for molecules in interstellar ices
Juris Kalvans
Processing by interstellar photons affects the composition of the icy mantles on interstellar grains. The rate of photodissociation in solids differs from that of molecules in the…
The Effects of Subsurface Chemistry in the Grain Mantles on the Deuterium Chemistry in Molecular Clouds
Juris Kalvans, Ivar Shmeld
The deuterium enrichment in molecules in dark molecular cloud cores and starforming regions is usually attributed to gas-phase chemistry. Here we examine the effects of surface and…
Temperature spectra of interstellar dust grains heated by cosmic-rays I: translucent clouds
Juris Kalvāns
Heating of whole interstellar dust grains by cosmic-ray (CR) particles affects the gas-grain chemistry in molecular clouds by promoting molecule desorption, diffusion, and chemical…
Ice chemistry in starless molecular cores
Juris Kalvans
Starless molecular cores are natural laboratories for interstellar molecular chemistry research. The chemistry of ices in such objects was investigated with a three-phase (gas, sur…
The effect of selective desorption mechanisms during interstellar ice formation
Juris Kalvans
Major components of ices on interstellar grains in molecular clouds - water and carbon oxides - occur at various optical depths. This implies that selective desorption mechanisms a…
Cosmic-ray-induced dissociation and reactions in warm interstellar ices
Juris Kalvans
Context. Cosmic ray particles that hit interstellar grains in dark molecular cores may induce whole-grain heating. The high temperature of a CR-heated grain allows energy barriers…
Cosmic-ray induced diffusion in interstellar ices
Juris Kalvans
Cosmic rays are able to heat interstellar dust grains. This may enhance molecule mobility in icy mantles that have accumulated on the grains in dark cloud cores. A three-phase astr…
Modeling of subsurface ice mantle on interstellar dust grains with astrochemical code ALCHEMIC (research note)
Juris Kalvans
Interstellar ices are layers of molecules deposited on !ne dust grains in dark and dense molecular cloud cores. Subsurface ice has been considered in a few astrochemical models, wh…
Modeling the processing of interstellar ices by energetic particles
Juris Kalvāns, Ivar Shmeld
Context. Interstellar ice is the main form of metal species in dark molecular clouds. Experiments and observations have shown that the ice is significantly processed after the free…
The Effect of an Inert Solid Reservoir on Molecular Abundances in Dense Interstellar Clouds
Juris Kalvans, Ivar Shmeld
The question, what is the role of freeze-out of chemical species in determining the molecular abundances in the interstellar gas is a matter of debate. We investigate a theoretical…
Subsurface chemistry of mantles of interstellar dust grains in dark molecular cores
Juris Kalvans, Ivar Shmeld
Context. The abundances of many observed compounds in interstellar molecular clouds still lack an explanation, despite extensive research that includes both gas and solid (dust-gra…