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The hydrogenation of polycyclic aromatic hydrocarbons (PAHs) is crucial to understanding molecular hydrogenation formation in the interstellar medium. This process also helps to elucidate the weakening of the aromatic bonds in PAHs, which…

Astrophysics of Galaxies · Physics 2025-09-03 S. Haid , K. Gugeler , J. Kästner , D. Campisi

We present measurements of 5-25 {\mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Megan Donahue , Geneviève E. de Messières , Robert W. O'Connell , G. Mark Voit , Aaron Hoffer , Brian R. McNamara , Paul E. J. Nulsen

Polycyclic aromatic hydrocarbons (PAHs) appear to be ubiquitous in terrestrial atmosphere as well as in the interstellar medium (ISM). In the astrophysical context presence of PAHs is interpreted by the observations of mid-IR emission bands…

Chemical Physics · Physics 2019-03-26 Rashmi Singh , Shantanu Rastogi

Using a large collection of near-infrared spectra (2.5-5.4 um) of Galactic HII regions and HII region-like objects, we perform a systematic investigation of the astronomical polycyclic aromatic hydrocarbon (PAH) features. 36 objects were…

Astrophysics of Galaxies · Physics 2015-06-18 Tamami I. Mori , Takashi Onaka , Itsuki Sakon , Daisuke Ishihara , Takashi Shimonishi , Ryou Ohsawa , Aaron C. Bell

Fragmentation is an important decay mechanism for polycyclic aromatic hydrocarbons (PAHs) under harsh interstellar conditions and represents a possible formation pathway for small molecules such as H2, C2H2, C2H4. Our aim is to investigate…

The mid-infrared spectra of large PAHs ranging from C54H18 to C130H28 are determined computationally using Density Functional Theory. Trends in the band positions and intensities as a function of PAH size, charge and geometry are discussed.…

Astrophysics · Physics 2012-08-27 Charles W. Bauschlicher, , Els Peeters , Louis J. Allamandola

We investigate the presence of silicon atoms adsorbed on the surface of interstellar polycyclic aromatic hydrocarbons (PAHs) to form SiPAH pi-complexes. We use quantum chemistry calculations to obtain structural, thermodynamic and mid-IR…

Astrophysics · Physics 2009-11-13 B. Joalland , A. Simon , C. J. Marsden , C. Joblin

Polycyclic aromatic hydrocarbons (PAHs) are commonly used as proxies for star formation, molecular gas content, and other interstellar medium (ISM) properties in our Galaxy and other galaxies. Given their abundance and brightness,…

Astrophysics of Galaxies · Physics 2026-03-24 Enrique Lopez-Rodriguez

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…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Dinalva A. Sales , M. G. Pastoriza , R. Riffel

We investigate the relations among the stellar continuum-subtracted 8 micron polycyclic aromatic hydrocarbon (PAH 8 micron) emission, 24 micron hot dust emission, and 160 micron cold dust emission in fifteen nearby face-on spiral galaxies…

We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 H II complexes in nine galaxies. Spectra obtained with the 6-m telescope of SAO RAS are used along with archival data from Spitzer and several…

Solar and Stellar Astrophysics · Physics 2015-06-22 M. S. Khramtsova , D. S. Wiebe , T. A. Lozinskaya , O. V. Egorov

We present experimental data on H2 formation processes on gas-phase polycyclic aromatic hydrocarbon (PAH) cations. This process was studied by exposing coronene radical cations, confined in a radio-frequency ion trap, to gas phase H atoms.…

Astrophysics of Galaxies · Physics 2018-09-05 N. Foley , S. Cazaux , D. Egorov , L. M. P. V. Boschman , R. Hoekstra , T. Schlatholter

We present a detailed study on the spatially resolved polycyclic aromatic hydrocarbon (PAH) emission properties in the (circum)nuclear region (NR) and extranuclear regions (ENRs) of M51a using Spitzer-IRS observations. Correlations among…

Astrophysics of Galaxies · Physics 2022-02-16 Rong Xuan Zang , Alexandros Maragkoudakis , Els Peeters

Superhydrogenated polycyclic aromatic hydrocarbons (PAHs) may be present in H-rich and ultraviolet-poor benign regions. The addition of excess H atoms to PAHs converts the aromatic bonds into aliphatic bonds, the strongest of which falls…

Astrophysics of Galaxies · Physics 2020-03-04 X. J. Yang , Aigen Li , R. Glaser

The physical and chemical conditions in photodissociation regions (PDRs) are largely determined by the influence of far ultraviolet radiation. Far-UV photons can efficiently dissociate molecular hydrogen, a process that must be balanced at…

Astrophysics of Galaxies · Physics 2018-06-08 P. Castellanos , A. Candian , H. Andrews , A. G. G. M. Tielens

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic Bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen…

Solar and Stellar Astrophysics · Physics 2015-06-19 L. Guzman-Ramirez , E. Lagadec , D. Jones , A. A. Zijlstra , K. Gesicki

Polycyclic aromatic hydrocarbons (PAHs) are believed to be ubiquitous in the interstellar medium. Yet, to date no specific PAH molecule has been identified. In this paper, a new observational avenue is suggested to detect individual PAHs,…

Astrophysics of Galaxies · Physics 2015-08-21 Yacine Ali-Haïmoud

Although H$_{2}$ is the simplest and the most abundant molecule in the Universe, its formation in the interstellar medium, especially in the photodissociation regions is far from being fully understood. According to suggestions, the…

Astrophysics of Galaxies · Physics 2023-07-26 David P. Jelenfi , Anita Schneiker , Attila Tajti , Gabor Magyarfalvi , Gyorgy Tarczay

We study the polarized infrared emission by Polycyclic Aromatic Hydrocarbons (PAHs), when anisotropically illuminated by UV photons. PAH molecules are modeled as planar disks with in-plane and out-of-plane vibrational dipoles. As first…

Astrophysics of Galaxies · Physics 2011-02-11 Lorenzo Sironi , Bruce T. Draine

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…