Related papers: Polyynyl-substituted PAH molecules and DIB carrier…
We have examined polycyclic aromatic hydrocarbon (PAH) excitation in a sample of 25 nearby face-on spiral galaxies using the ratio of mid-infrared PAH emission to dust mass. Within 11 of the galaxies, we found that the PAH excitation was…
This study presents optical and near-infrared photometric observations, alongside mid-infrared spectroscopic data from the ISO SWS instrument, to examine potential correlations between Aromatic Infrared Band (AIB) features and the optical…
One of the major challenges to identification of the 3.3, 6.2, 7.7, 8.6, and 11.3um interstellar IR emission bands with polycyclic aromatic hydrocarbon (PAH) molecules has been the recent detection of these bands in regions with little UV…
Context. The 3.3 $\mu$m aromatic C-H stretching band of polycyclic aromatic hydrocarbon (PAH) molecules seen in a wide variety of astrophysical regions is often accompanied by a series of weak satellite bands at ~3.4-3.6 $\mu$m. One of…
The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 micrometer, commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules, have been recently ascribed to coal- or kerogen-like organic nanoparticles…
The discovery of the first diffuse interstellar bands (DIBs) dates back to the pioneering years of stellar spectroscopy. Today, we know about 300 absorption structures of this kind. There exists a great variety of the profiles and…
Virtually all detailed gas-phase models of the chemistry of dense interstellar clouds exclude polycyclic aromatic hydrocarbons (PAH's). This omission is unfortunate because from the few studies that have been done on the subject, it is…
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(HI), and dust reddening, E(B-V). Since CaII absorbers in quasar (QSO)…
We decompose the observed 7.7 $\mu$m polycyclic aromatic hydrocarbon (PAH) emission complexes in a large sample of over 7000 mid-infrared spectra of the interstellar medium (ISM) using spectral cubes observed with the Spitzer/IRS-SL…
Are the organic molecules crucial for life on Earth abundant in early-epoch galaxies? To address this, we searched for organic molecules in extragalactic sources via their absorption features, known as diffuse interstellar bands (DIBs).…
We investigate the emission properties of polycyclic aromatic hydrocarbons (PAHs) in various metallicity environments with the Infrared Spectrograph on board Spitzer. Local giant HII regions are used as references as they enable access to…
A large number of interstellar absorption features at ~ 4000\AA\ -- 1.8 {\mu}m, known as the "diffuse interstellar bands" (DIBs), remains unidentified. Most recent works relate them to large polycyclic aromatic hydrocarbon (PAH) molecules…
Using the Mid-Infrared Spectrometer on board the Infrared Telescope in Space and the low-resolution grating spectrometer (PHT-S) on board the Infrared Space Observatory, we obtained 820 mid-infrared (5 to 12 $\mu$m) spectra of the diffuse…
We study the Polycyclic Aromatic Hydrocarbons (PAH) bands, ionic emission lines, and Mid-infrared continuum properties, in a sample of 171 emission line galaxies taken from literature plus 15 new active galactic nuclei (AGN) Spitzer…
Nitrogen-bearing polycyclic aromatic hydrocarbons (N-PAHs) are key precursors to complex organic molecules in both the interstellar medium and the nitrogen-rich planetary atmospheres. Despite the recent detections of nitrogen-functionalized…
Polycyclic aromatic hydrocarbons (PAHs) play a critical role in the reprocessing of stellar radiation and in balancing the heating and cooling processes in the interstellar medium (ISM), but appear to be destroyed in HII regions. However,…
The molecular carriers of the ubiquitous absorption features called the diffuse interstellar bands (DIBs) have eluded identification for many decades, in part because of the enormous parameter space spanned by the candidates and the limited…
We examine the annihilation of positrons on polycyclic aromatic hydrocarbon (PAH) molecules in interstellar medium conditions. We estimate the annihilation rates of positrons on PAHs by a semi-empirical approach. We show that PAHs can play…
Clusters of polycyclic aromatic hydrocarbon (PAH) molecules are modelled using explicit all-atom potentials using a rigid body approximation. The PAH's considered range from pyrene (C10H8) to circumcoronene (C54H18), and clusters containing…
We present spectra of a sample of Herbig Ae and Be (HAeBe) stars obtained with the Infrared Spectrograph on the Spitzer Space Telescope. All but one of the Herbig stars show emission from polycyclic aromatic hydrocarbons (PAHs) and seven of…