Related papers: Modeling the processing of interstellar ices by en…
Models and observations suggest that ice-particle aggregation at and beyond the snowline dominates the earliest stages of planet-formation, which therefore is subject to many laboratory studies. However, the pressure-temperature gradients…
Infrared dark clouds (IRDCs) are cold, dense regions of the interstellar medium (ISM) that are likely to represent the initial conditions for massive star formation. It is thus important to study the physical and chemical conditions of…
Context. Recent Monte Carlo simulations and laboratory studies of interstellar ices have proposed an alternative pathway involving the radical-molecule H-atom abstraction reaction in the overall mechanism of methanol (CH3OH) formation in…
My thesis work aims to study the inter-relation between various physical and chemical conditions in a wide range of astrophysical environments. Our studied regions range from the super-hot regions (i.e., nebular, photon-dominated, or…
Water ice is important for the evolution and preservation of life. Identifying the distribution of water ice in debris disks is therefore of great interest in the field of astrobiology. Furthermore, icy dust grains are expected to play…
Ethanethiol (C$_2$H$_5$SH), a molecule detected in the interstellar medium (ISM), indicates the rich chemistry involving sulfur atoms. However, its behavior at low temperatures remains elusive, particularly the reported transition from an…
Hydrogen sulfide (H$_2$S) is thought to be efficiently formed on grain surfaces through the successive hydrogenation of S atoms. Its non-detection so far in astronomical observations of icy dust mantles thus indicates that effective…
The presence of methanol among the common ice components in interstellar clouds and protostellar envelopes has been confirmed by the James Webb Space Telescope. Methanol is often detected in the gas phase toward lines of sight shielded from…
We present observations of the stretching mode of 13CO2 ice along 13 lines of sight in the Galaxy, using the Short Wavelength Spectrometer on board of the Infrared Space Observatory. Remarkable variations are seen in the absorption band…
Interstellar grains are known to be important actors in the formation of interstellar molecules such as H$_2$, water, ammonia, and methanol. It has been suggested that the so-called interstellar complex organic molecules (iCOMs) are also…
Our knowledge about the physical processes determining the activity of comets were mainly influenced by several extremely successful space missions, the predictions of theoretical models and the results of laboratory experiments. However,…
Mantles of iced water, mixed with CO, H2CO, and CH3OH are formed during the so called prestellar core phase. In addition, radicals are also thought to be formed on the grain surfaces, and to react to form complex organic molecules later on,…
We present a new gas-grain chemical model to constrain the effect of grain size distribution on molecular abundances in starless and pre-stellar cores. We introduce grain-size dependence simultaneously for cosmic-ray (CR)-induced desorption…
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 input for a modified rate-equation astrochemical model,…
Methanol is a common component of interstellar and circumstellar ice mantles and is often used as an evolution indicator in star-forming regions. The observations of gas-phase methanol in the interiors of dense molecular clouds at…
Interstellar dust grains do not have a single well-defined origin. Stars are demonstrably dust producers, but also efficient destroyers of cosmic dust. Dust destruction in the ISM is believed to be the result of SN shocks hitting the…
It has been suggested that star-forming galaxies may host a substantial, dark reservoir of gas in the form of planetary-mass molecular clouds that are so cold that $\text{H}_{2}$ can condense. Here we investigate the process of tidal…
UV irradiation of simple ices is proposed to efficiently produce complex organic species during star- and planet-formation. Through a series of laboratory experiments, we investigate the effects of the H2O concentration, the dominant ice…
The presence of dust can strongly affect the chemical composition of the interstellar medium. We model the chemistry in photodissociation regions (PDRs) using both gas-phase and dust-phase chemical reactions. Our aim is to determine the…
Star formation is one of the least understood processes in cosmic evolution. It is difficult to formulate a general theory for star formation in part because of the wide range of physical processes involved. The interstellar gas out of…