Results tagged “Astrochemistry”

At the low temperatures (∼10 K) and high densities (∼100,000 H2 molecules per cc) of molecular cloud cores and protostellar envelopes, a large amount of molecular species (in particular those containing C and O) freeze-out onto dust grain surfaces.

We study the chemical evolution of H2O:CO:NH3 ice mixtures irradiated with soft X-rays, in the range 250-1250 eV. We identify many nitrogen-bearing molecules such as e.g., OCN-, NH4+ , HNCO, CH3CN, HCONH2, and NH2COCONH2.

Non-thermal desorption from icy grains containing H2CO has been invoked to explain the observed H2CO gas phase abundances in ProtoPlanetary Disks (PPDs) and Photon Dominated Regions (PDRs).

Formic acid (HCOOH) and carbon dioxide (CO2) are simple species that have been detected in the interstellar medium.

A number of recent experimental studies have shown that solid-state complex organic molecules (COMs) can form under conditions that are relevant to the CO freeze-out stage in dense clouds.

Since the Archean, N2 has been a major atmospheric constituent in Earth's atmosphere.

Iram 30-m Observations towards eight protostellar outflow sources were taken in the 96-176 GHz range. Transitions of CH3OH and CH3CHO were detected in seven of them.

Cyanogen (NCCN) is the simplest member of the dicyanopolyynes group, and has been proposed as a major source of the CN radical observed in cometary atmospheres. Although not detected through its rotational spectrum in the cold interstellar medium, this very stable species is supposed to be very abundant.

Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such as Enceladus, a moon of Saturn.

The identification of the carriers of the diffuse interstellar bands (DIBs) remains to be established, with the exception of five bands attributed to C60+, although it is generally agreed that DIB carriers should be large carbon-based molecules (with ~10-100 atoms) in the gas phase, such as polycyclic aromatic hydrocarbons (PAHs), long carbon chains or fullerenes.

We present results from one-dimensional atmospheric simulations investigating the effect of varying the carbon-to-oxygen (C/O) ratio on the thermal structure, chemical composition and transmission and emission spectra, for irradiated hydrogen-dominated atmospheres.

Small hydrocarbons are an important organic reservoir in protostellar and protoplanetary environments. Constraints on desorption temperatures and binding energies of such hydrocarbons are needed for accurate predictions of where these molecules exist in the ice vs. gas-phase during the different stages of star and planet formation.

Typically, H3+ is formed by collisions involving hydrogen gas, but its chemistry at the molecular level is relatively unknown. When organic molecules are hit by a laser pulse, they are ionized and the reaction begins.

Some of the exoplanets so far observed show featureless or flat transmission spectra, possibly indicating the existence of clouds and/or haze in their atmospheres.

Water ice is abundant in protoplanetary disks. Its sticking properties are therefore important during phases of collisional growth. In this work, we study the sticking and rolling of 1.1 mm ice grains at different temperatures. We find a strong increase in sticking between 175 K to 200 K which levels off at higher temperatures.

In the laboratory, the photo-and thermochemical evolution of ices, made of simple molecules of astrophysical relevance, always leads to the formation of semi-refractory water-soluble organic residues.

We report a computational study of the stability and infrared (IR) vibrational spectra of neutral and singly ionised fullerene cages containing between 44 and 70 carbon atoms.

Young stars are often surrounded by a protoplanetary disk where planets are forming. Astronomers study the composition of protoplanetary disks to better understand how planets, like Earth, formed and evolved into their modern chemical composition.

Protoplanetary disks are dust-rich structures around young stars. The crystalline and amorphous materials contained within these disks are variably thermally processed and accreted to make bodies of a wide range of sizes and compositions, depending on the heliocentric distance of formation.

The cometary materials are thought to be the reservoir of primitive materials in the solar system. The recent detection of glycine and CH3NH2 by the ROSINA mass spectrometer in the coma of 67P/Churyumov-Gerasimenko suggests that amino acids and their precursors have been formed in such an early evolutionary phase of the Solar System.

« Previous  1 2 3 4 5 6 7 8 9 10 11 12