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The search for large polycyclic aromatic hydrocarbons (PAHs) with over 100 carbon atoms is crucial to resolving the origin of unidentified infrared emission (UIE) bands. These bands are commonly observed in nebulae and the interstellar…

Astrophysics of Galaxies · Physics 2025-08-22 Yi Shao , Yong Zhang , Xu-Jia Ouyang , Chuan-Peng Zhang

Infrared (IR) emission spectra are calculated for dust composed of mixtures of amorphous silicate and graphitic grains, including varying amounts of polycyclic aromatic hydrocarbon (PAH) particles. The models are constrained to reproduce…

Astrophysics · Physics 2008-11-26 B. T. Draine , Aigen Li

NGC 7023 is a well-studied reflection nebula, which shows strong emission from polycyclic aromatic hydrocarbon (PAH) molecules in the form of aromatic infrared bands (AIBs). The spectral variations of the AIBs in this region are connected…

Astrophysics of Galaxies · Physics 2016-05-25 B. A. Croiset , A. Candian , O. Berné , A. G. G. M. Tielens

Polycyclic Aromatic Hydrocarbons are prevalent in the universe and interstellar medium but are primarily attributed to anthropogenic sources on Earth, such as fossil fuel combustion and firewood burning. Drawing upon the idea of PAHs as…

Earth and Planetary Astrophysics · Physics 2025-01-14 Dwaipayan Dubey , Ravi Kopparapu , Barbara Ercolano , Karan Molaverdikhani

The exact nature of the 2175 Angstrom extinction bump, the strongest spectroscopic absorption feature superimposed on the interstellar extinction curve, remains unknown ever since its discovery in 1965. Popular candidate carriers for the…

Astrophysics of Galaxies · Physics 2023-08-10 Qi Lin , X. J. Yang , Aigen Li

The photochemistry of ices with polycyclic aromatic hydrocarbons (PAHs) has been extensively studied, but to date no investigation has been made of PAHs in interaction with low numbers (n < 4) of molecules of water. We performed…

Astrophysics of Galaxies · Physics 2017-03-15 J. A. Noble , C. Jouvet , C. Aupetit , A. Moudens , J. Mascetti

We have developed an excitation model for small molecules including radiative pumping by dust photons from near infrared to submillimeter wavelengths. This model applies to molecules within bright photodissociation regions in galactic…

Astrophysics · Physics 2009-09-25 M. Giard , J. L. Puget , E. Crete , F. Scoupe

We introduce a novel model to spectroscopically constrain the mid-infrared (MIR) extinction/attenuation curve from 3--17 um, using Polycyclic Aromatic Hydrocarbon (PAH) emission drawn from an AKARI-Spitzer extragalactic cross-archival…

The cosmic-ray ionization rate ($\zeta$, s$^{-1}$) plays an important role in the interstellar medium. It controls ion-molecular chemistry and provides a source of heating. Here we perform a grid of calculations using the spectral synthesis…

Astrophysics of Galaxies · Physics 2021-01-13 Gargi Shaw , G. J. Ferland

We investigate in the mid-IR the spatial properties of the PAHs emission in the disk of HD179218. We obtained mid-IR images in the PAH1, PAH2 and Si6 filters at 8.6, 11.3 and 12.5 mu, and N band low-resolution spectra using CanariCam on the…

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

We study the photoevaporation of molecular clumps exposed to a UV radiation field including hydrogen-ionizing photons ($h\nu > 13.6$ eV) produced by massive stars or quasars. We follow the propagation and collision of shock waves inside…

Astrophysics of Galaxies · Physics 2017-07-28 Davide Decataldo , Andrea Ferrara , Andrea Pallottini , Simona Gallerani , Livia Vallini

We present a new methodology for simulating mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) in galaxy evolution simulations. To do this, we combine theoretical models of PAH emission features as they respond to varying…

In order to find out capable molecular source of astronomically well observed infrared (IR) spectrum, asymmetric molecular configuration polycyclic aromatic hydrocarbon (PAH) was analyzed by the density functional theory (DFT) analysis.…

Astrophysics of Galaxies · Physics 2015-10-27 Norio Ota

The fullerene C$_{60}$, one of the largest molecules identified in the interstellar medium (ISM), has been proposed to form top-down through the photo-chemical processing of large (more than 60 C-atoms) polycyclic aromatic hydrocarbon (PAH)…

Instrumentation and Methods for Astrophysics · Physics 2019-02-20 Weiwei Zhang , Yubing Si , Junfeng Zhen , Tao Chen , Harold Linnartz , Alexander G. G. M. Tielens

Fragments from organic molecule dissociation (such as reactive ions and radicals) can form interstellar complex molecules like amino acids. The goal of this work is to experimentally study photoionization and photodissociation processes of…

Astrophysics · Physics 2007-05-23 S. Pilling , A. C. F. Santos , H. M. Boechat-Roberty

Aim: The cold molecular gas mass is one of the crucial, yet challenging parameters in galaxy evolution studies. Here, we introduce a new calibration for estimating molecular gas masses using mid-infrared (MIR) photometry. This topic is…

Astrophysics of Galaxies · Physics 2024-10-30 Irene Shivaei , Leindert Boogaard

The PHANGS survey uses ALMA, HST, VLT, and JWST to obtain an unprecedented high-resolution view of nearby galaxies, covering millions of spatially independent regions. The high dimensionality of such a diverse multi-wavelength dataset makes…

The infrared signature of polycyclic aromatic hydrocarbons (PAHs) are present in many protostellar disks and these speciesare thought to play an important role in heating of the gas in the photosphere. We aim to consider PAH cluster…

Earth and Planetary Astrophysics · Physics 2021-09-01 K. Lange , C. Dominik , A. G. G. M. Tielens
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