Related papers: Is H3+ cooling ever important in primordial gas?
Molecular oxygen has been confirmed as the fourth most abundant molecule in cometary material O$_2$/H$_2$O $\sim 4$ %) and is thought to have a primordial nature, i.e., coming from the interstellar cloud from which our solar system was…
In primordial gas, molecular hydrogen forms primarily through associative detachment of H- and H, thereby destroying the H-. The H- anion can also be destroyed by a number of other reactions, most notably by mutual neutralization with…
The energy transfer among the components in a gas determines its fate. Especially at low temperatures, inelastic collisions drive the cooling and the heating mechanisms. In the early Universe as well as in zero- or low- metallicity…
In diffuse interstellar clouds the chemistry that leads to the formation of the oxygen bearing ions OH+, H2O+, and H3O+ begins with the ionization of atomic hydrogen by cosmic rays, and continues through subsequent hydrogen abstraction…
An X-ray background in the early Universe enhances molecular hydrogen formation, the main coolant of primordial gas, thereby lowering the threshold for Pop III star formation. Continuing our series on X-ray impacts on Pop III star…
Deuterated interstellar molecules frequently have abundances relative to their main isotopologues much higher than the overall elemental D-to-H ratio in the cold dense interstellar medium. The H$_3^+$ and its isotopologues play a key role…
The astrochemistry of the HnO+ (n=1..3) ions is important as the main gas-phase formation route for water, and as tracer of the interstellar ionization rate by cosmic rays and other processes. While interstellar H3O+ has been known since…
Recent interferometer observations have found that the D2O/HDO abundance ratio is higher than that of HDO/H2O by about one order of magnitude in the vicinity of low-mass protostar NGC 1333-IRAS 2A, where water ice has sublimated. Previous…
Water is the main component of interstellar ice mantles, is abundant in the solar system and is a crucial ingredient for life. The formation of this molecule in the interstellar medium cannot be explained by gas-phase chemistry only and its…
The standard treatment of cooling in Cold Dark Matter halos assumes that all of the gas within a ``cooling radius'' cools and contracts monolithically to fuel galaxy formation. Here we take into account the expectation that the hot gas in…
Gas-phase complex organic molecules have been detected toward a range of high- and low-mass star-forming regions at abundances which cannot be explained by any known gas-phase chemistry. Recent laboratory experiments show that UV…
Gas-phase processes were long thought to be the key formation mechanisms for complex organic molecules in star-forming regions. However, recent experimental and theoretical evidence has cast doubt on the efficiency of such processes.…
Aims: We aim to simulate radial profiles of molecular abundances and the gas temperature in cold and heavily shielded starless cores by combining chemical and radiative transfer models. Methods: A determination of the dust temperature in a…
The formation of methanol (CH3OH) on icy grain mantles during the star formation cycle is mainly associated with the CO freeze-out stage. Yet there are reasons to believe that CH3OH also can form at an earlier period of interstellar ice…
Since its discovery in the aurorae of Jupiter ~30 years ago, the H$_{3}^{+}$ ion has served as an invaluable probe of giant planet upper atmospheres. However, the vast majority of monitoring of planetary H$_{3}^{+}$ radiation has followed…
(Abridged) We aim to enlarge the number of known hot corinos and carry out a first comparative study with hot cores. The ultimate goal is to understand whether complex organic molecules form in the gas phase or on grain surfaces, and what…
The theory for the formation of the first population of stars (Pop III) predicts a IMF composed predominantly of high-mass stars, in contrast to the present-day IMF, which tends to yield stars with masses less than 1 M_Solar. The leading…
Diffuse interstellar clouds show large abundances of H_3^+ which can be maintained only by a high ionization rate of H_2. Cosmic rays are the dominant ionization mechanism in this environment, so the large ionization rate implies a high…
The study of the composition of brown dwarf atmospheres helped to understand their formation and evolution. Similarly, the study of exoplanet atmospheres is expected to constrain their formation and evolutionary states. We use results from…
Recent models of the envelopes of seven massive protostars are used to analyze observations of H3+ infrared absorption and H13CO+ submillimeter emission lines toward these stars, and to constrain the cosmic-ray ionization rate zeta. The…