We examine observational characteristics of multi-phase turbulent flows in the diffuse interstellar medium (ISM) using a synthetic radiation field of atomic and molecular lines. We consider the multi-phase ISM which is formed by thermal instability under the irradiation of UV photons with moderate visual extinction AV ∼ 1. Radiation field maps of C, C, and CO line emissions were generated by ca...

Context. Polycyclic aromatic hydrocarbon (PAH) molecules play an essential role in the prebiotic compound evolution network interstellar medium (ISM). A recent experimental study revealed that large, astronomically relevant PAH-organic molecule clusters are gradually formed through ion-molecule collision reaction pathway presence of a strong radiation field. Aims. We present theoretical survey ...

Acetamide (CH3CONH2) has been detected in emission and absorption toward the star-forming region Sagittarius B2(N) with the 100 m Green Bank Telescope (GBT) by means of four A-species and four E-species rotational transitions. All transitions have energy levels less than 10 K. The Sgr B2(N) cloud is known to have a cold halo with clumps of gas at several different velocities. Absorption feature...

Gradients in molecular abundances along the TMC-1 ridge have been observed by several authors, most recently in a comprehensive study by Pratap et al. These can be explained by there being a di†erence in density, C/O ratio, or chemical evolutionary state along the ridge. The presence at the carbonrich ““ cyanopolyyne peak ÏÏ (CP) of speciÐc oxygen-bearing molecules, believed to be products of g...

Planar polycyclic aromatic hydrocarbons (PAHs) are candidates for the diffuse interstellar band (DIB) carriers. Nanometer-size Fe metallic particles, expected to be present during astrophysical graphite growth, are catalytic for formation of a related species—large tubular PAH molecules. We propose that tubular PAH molecules are a component of the interstellar medium. Electronic structure calcu...

Polycyclic aromatic hydrocarbon (PAH) molecules, ubiquitously seen in the interstellar medium (ISM) of our own and external galaxies, might have been incorporated into comets if they are formed from relatively unprocessed interstellar matter. The detection of PAHs in comets would be an important link between the ISM and comets. This review compiles our current knowledge on cometary PAHs, based ...

A sample of 59 sight lines to reddened Galactic OB stars was examined for correlations of the strength of the CO Fourth Positive (AΠ − XΣ) absorption band system with the ultraviolet interstellar extinction curve parameters. We used archival high-dispersion NEWSIPS IUE spectra to measure the CO absorption for comparison to parametric fits of the extinction curves from the literature. A strong c...

We present the results of imaging spectroscopy of the reflection nebula vdB 133, obtained with the infrared camera and circular variable filter wheel on the Infrared Space Observatory (1S0). Our observations reveal the infrared emission features (IEFs), at 6.2, 7.7, 8.6, 11.3, and 12.7 pm, and associated 5 – 15 pm continuum emission. The stellar system illuminating vdB 133 has the lcjwest ratio...

We propose to observe the mid-IR spectroscopic signatures of biologically important organic molecules in molecular clouds, protostellar envelopes, planet forming systems, and planetary debris disks. In addition to yielding a more complete census of organic materials in the ISM, these observations will provide insight into how these molecules are physically and chemically processed into the chem...

Although still poorly understood, the chemistry that occurs on the surfaces of interstellar dust particles profoundly affects the growth of molecules in the interstellar medium. An important set of surface reactions produces icy mantles of manymonolayers in cold and dense regions. The monolayers are dominated by water ice, but also contain CO, CO2, and occasionally methanol, as well as minor co...