Related papers: Reactive Desorption of CO Hydrogenation Products u…
At the high densities and low temperatures found in star forming regions, all molecules other than H2 should stick on dust grains on timescales shorter than the cloud lifetimes. Yet these clouds are detected in the millimeter lines of…
Molecular clouds are the cold regions of the Milky Way where stars form. They are enriched by rather complex molecules. Many of these molecules are believed to be synthesized on the icy surfaces of the interstellar submicron-sized dust…
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 are at work. An astrochemical model of a contracting low-mass…
In regions where stars form, variations in density and temperature can cause gas to freeze-out onto dust grains forming ice mantles, which influences the chemical composition of a cloud. The aim of this paper is to understand in detail the…
Aims: The gas-phase abundance of methanol in dark quiescent cores in the interstellar medium cannot be explained by gas-phase chemistry. In fact, the only possible synthesis of this species appears to be production on the surfaces of dust…
The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation…
We study the photo-desorption occurring in H$_2$O:CO:NH$_3$ ice mixtures irradiated with monochromatic (550 and 900 eV) and broad band (250--1250 eV) soft X-rays generated at the National Synchrotron Radiation Research Center (Hsinchu,…
A longstanding problem in astrochemistry is how molecules can be maintained in the gas phase in dense inter- and circumstellar regions. Photodesorption is a non-thermal desorption mechanism, which may explain the small amounts of observed…
Hydrogenation reactions of CO in inter- and circumstellar ices are regarded as an important starting point in the formation of more complex species. Previous laboratory measurements by two groups on the hydrogenation of CO ices resulted in…
In molecular clouds at temperatures as low as 10 K, all species except hydrogen and helium should be locked in the heterogeneous ice on dust grain surfaces. Nevertheless, astronomical observations have detected over 150 different species in…
Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out,…
We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense-cloud core to a protostellar core, by solving a gas-grain reaction network applied to a 1-D radiative hydrodynamic model…
Methanol is formed via surface reactions on icy dust grains. Methanol is also detected in the gas-phase at temperatures below its thermal desorption temperature and at levels higher than can be explained by pure gas-phase chemistry. The…
Non-thermal desorption from icy grains containing H$_2$CO has been invoked to explain the observed H$_2$CO gas phase abundances in ProtoPlanetary Disks (PPDs) and Photon Dominated Regions (PDRs). Photodesorption is thought to play a key…
The interaction of CO with the Fe3O4(001)-(rt2xrt2)R45{\deg} surface was studied using temperature programmed desorption (TPD), scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh…
The desorption of molecular species from ice mantles back into the gas phase in molecular clouds results from a variety of very poorly understood processes. We have investigated three mechanisms; desorption resulting from H_2 formation on…
Context. It is generally agreed that hydrogenation reactions dominate chemistry on grain surfaces in cold, dense molecular cores, saturating the molecules present in ice mantles. Aims. We present a study of the low temperature reactivity of…
We investigate molecular evolution in a star-forming core that is initially a hydrostatic starless core and collapses to form a low-mass protostar. The results of a one-dimensional radiation-hydrodynamics calculation are adopted as a…
Experiments on the hydrogenation of CO on crystalline and amorphous ice at 15 K were carried out to investigate the structural effects of the ice surface. The effective rate of H atom addition to CO on the amorphous ice was found to be…
Recent ALMA (Atacama Large Millimeter/submillimeter Array) observations of young protostellar objects detected warm SO emission, which could be associated with a forming protostellar disk. In order to investigate if such warm gas can be…