The integrated luminosity from the features of the polycyclic aromatic hydrocarbons (PAHs) exceeds the luminosity from atomic and molecular emission lines in the star-forming regions in galaxies and is a […]
![PAH fraction anti-correlates with log([S iii]/[S ii]) (ionization parameter tracer) for thousands H ii regions in 42 PHANGS-JWST galaxies. Panel (a, b) shows all ∼ 17200 analyzed H ii regions, while ∼ 5600 brightest “resolved” H ii regions are shown on Panels (c, d). The dashed red line shows the best-fit linear regression to the “resolved” sample defined by Eq. 4. Histograms on panels (b, d) show how the logarithmic residuals after subtracting this linear trend depend on metallicity. Color on panels (a, c) denotes gas-phase oxygen abundance; red contours show the probability density of the high-metallicity (12 + log(O/H) > 8.2) points (levels correspond to 50, 65, 80, 95 and 99 percentile intervals). The Spearman correlation coefficient (ρ) and RMS scatter around the linear fit are reported on panels (a, c). -- astro-ph.GA](https://i0.wp.com/astrobiology.com/wp-content/uploads/2025/09/Polycyclic-aromatic-hydrocarbons-destruction.png?resize=1200%2C720&ssl=1)
Polycyclic aromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM) of Solar metallicity galaxies, where they play a critical role in ISM heating, cooling, and reprocessing stellar radiation.
Planetary nebulae are sites where ejected stellar material evolves into complex molecules, but the precise physical conditions and chemical routes that govern these processes are unclear.
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.
![Distribution of the 11.0/11.2 PAH band ratio versus stellar effective temperature for our HAeBe sample. Reference stars (SR 21A, PDS 144N, HD 97300) shows different ionization regimes. The shaded regions approximate PDR-like ranges from JWST data, whereas very low ratios occur at 5000–6000 K suggestive of neutral PAHs in low mass disk. MWC 137, which is showing very low ionization is likely an evolved B[e] star rather than an HAeBe star. -- astro-ph.SR](https://i0.wp.com/astrobiology.com/wp-content/uploads/2025/06/Polycyclic-Aromatic-Hydrocarbons-In-The.png?resize=1200%2C720&ssl=1)
We present a comprehensive mid-infrared spectroscopic survey of 124 Herbig Ae/Be stars using newly processed Spitzer/IRS spectra from the newly released CASSISjuice database.
Two key questions of the chemistry of Polycyclic Aromatic Hydrocarbons (PAHs) in the interstellar medium (ISM) are addressed: i) the way carbon is returned from PAHs to the interstellar gas […]
Strong anharmonic coupling between vibrational states in polycyclic aromatic hydrocarbons (PAH) produces highly mixed vibrational transitions that challenge the current understanding of the nature of the astronomical mid-infrared PAH emission […]
Polycyclic Aromatic Hydrocarbons (PAHs) have been detected throughout the universe where they play essential roles in the evolution of their environments.
![Synthetic spectra for a XPAH = 10−6 at temperatures of 800 K (top), 1200 K (middle), and 1600 K (bottom). Similar to Fig. A1, with constant C/O (0.55) and varying metallicities ([Fe/H]) are displayed for 0.1 (left) in green, 1 (middle) in cyan and 10 (right) in yellow. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/11/Polycyclic-Aromatic-Hydrocarbons-in-Exoplanet-Atmospheres.png?resize=1200%2C720&ssl=1)
In this paper, we explore the detectability of polycyclic aromatic hydrocarbons (PAHs) under diverse planetary conditions, aiming to identify promising targets for future observations of planetary atmospheres.
The first all-sky, high-resolution, 3D map of the optical extinction curve of the Milky Way (Zhang & Green 2024) revealed an unexpected steepening of the extinction curve in the moderate-density, […]
