PAH Archives

Schematic of a PHA granule structure from Maestro and Sanz (Reference Maestro and Sanz2017). -- International Journal of Astrobiology

Astrochemistry, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Extremeophiles and Extreme Environments, Status Report

Applications of Microbial Bioplastic Polyhydroxyalkanoates as Biosignatures for Astrobiological Detection

by Keith CowingDecember 19, 2024December 19, 2024

Determining a reliable method to detect life on another planet is an essential first step in the pursuit of discovering extraterrestrial life.

pahfit decomposition of the combined SL+LL Spitzer -IRS spectrum of galaxy SSGSS-016. The fit (orange line) is synthesized using the following components: Dust features (light blue lines), atomic and H2 lines (magenta lines), continuum (yellow lines; the total continuum emission is shown as a purple line), and attenuation (dashed black line). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Status Report

A Sensitivity Analysis of the Modeling of Polycyclic Aromatic Hydrocarbon Emission in Galaxies

by Keith CowingDecember 5, 2024

We have conducted a sensitivity analysis on the mid-infrared spectral decomposition of galaxies and the modeling of the PAH emission spectrum with the NASA Ames PAH Infrared Spectroscopic Database (PAHdb) […]

Anharmonic IR cascade emission spectra of a) indene in the CH stretch region (2700 – 3400 cm−1 ; 3.7 – 2.9 µm) at starting internal energies of 2, 4, 6, and 8 eV. -- MNRAS

Astrochemistry, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Battle of the CH Motions: aliphatic vs. Aromatic Contributions to Astronomical PAH Emission and Exploration of the Aliphatic, Aromatic, and Ethynyl CH Stretches

by Keith CowingNovember 19, 2024November 19, 2024

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 […]

Comparison of 2D distribution of A(V), R(V), qPAH for dust clouds. For A(V) and R(V) maps, we select high-quality stars from Zhang & Green (2024), and remove lines of sight where only partial extinction is covered by XP. For qPAH map, we remove lines of sight where the qPAH map is of low quality (χ 2 /DOF > 3 or qPAH/σ(qPAH) < 3), or that cross multiple clouds (Equation 1). The binning method and selection of stars in the 2D maps are described in Appendix A. Despite different baselines and finer structures in different maps, all clouds tend to have lower R(V ) at high-qPAH regions, as indicated quantitatively on the per-star basis in Figure 5 -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Mapping, Geodesy, Cartography, Bathymetry, Status Report, Stellar Cartography

Dust Extinction-curve Variation In The Translucent Interstellar Medium Is Driven By PAH Growth

by Keith CowingOctober 31, 2024October 31, 2024

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, […]

JWST/NIRCam F335M image of 30 Dor. The blue box represents the field of view of the MIRI/MRS Channel 1. The inset shows the spectroscopic FOVs: NIRSpec (green), MIRI/MRS Channel 1 (blue), MIRI/MRS Channel 2 (pink), and MIRI/MRS Channel 3 (yellow). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Imaging & Spectroscopy, Status Report

A Study of Polycyclic Aromatic Hydrocarbon Emission in 30 Dor as seen by JWST

by Keith CowingOctober 29, 2024October 29, 2024

Polycyclic aromatic hydrocarbons (PAHs) are responsible for strong mid-IR emission features near star-forming regions. It is well known that low-metallicity environments exhibit weaker PAH emission, but it is not clear […]

A representation of 1-cyanopyrene detected in space. Credit: NSF/NSF NRAO/AUI/S. Dagnello.

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Press Release

The Largest Molecule Ever Detected Using Radioastronomy

by Keith CowingOctober 25, 2024October 25, 2024

The discovery of a four-ring carbon molecule in a distant interstellar cloud may help to reveal how our own solar system formed.

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Press Release

Molecules That Store Carbon Discovered In A Distant Interstellar Cloud

by Keith CowingOctober 24, 2024

The discovery of pyrene derivatives in a distant interstellar cloud may help to reveal how our own solar system formed.

CO and PAH emission in one nearby galaxy. The left panel shows an inclination-corrected ALMA CO(2-1) image of NGC 2903 with contours at 1.25, 3.1, 31, and 100 K km s−1 . The right panel shows a predicted CO(2-1) intensity map based on JWST F770WPAH and the prescription in Eq. 5. The contours are the same as on the left panel, and they show a very close correspondence between CO and PAH emission. At the same time, CO(2-1) emission is underestimated in the bar ends, highlighting improvements to be explored in future work. This figure also shows the improved sensitivity of JWST compared to ALMA at recovering faint emission, with the 5σ RMS noise indicated on each colorbar. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Interstellar, Status Report

Polycyclic Aromatic Hydrocarbon and CO(2-1) Emission at 50-150 pc Scales in 66 Nearby Galaxies

by Keith CowingOctober 10, 2024October 10, 2024

Combining Atacama Large Millimeter/sub-millimeter Array CO(2-1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2-1) and polycyclic aromatic hydrocarbon (PAH) emission at ~100 pc resolution in […]

Two-dimensional fits of U, qPAH, and Σd as a function of a combination of the resolved stellar mass and star formation rate. Top row: 2D histograms of the Σ⋆–ΣSFR plane, where the bin values show the average U (left column), qPAH (center column), and Σd (right column). The light bins are calculated for all pixels passing the 3σ S/N cut, and the bright bins are calculated for pixels passing that same cut and that that have Σ⋆ and ΣSFR above the completeness thresholds. The 2D fit uses the standard deviations within each bin as errors in the linear regression. Bottom row: The x-axis shows the best-fit using both Σ⋆ and ΣSFR. The y-axis shows the observed data. The best-fit coefficients are reported in Table 5. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Status Report

The Resolved Behavior of Dust Mass, Polycyclic Aromatic Hydrocarbon Fraction, and Radiation Field in ~ 800 Nearby Galaxies

by Keith CowingOctober 8, 2024October 8, 2024

We present resolved 3.6−250 μm dust spectral energy distribution (SED) fitting for ∼800 nearby galaxies. We measure the distribution of radiation field intensities heating the dust, the dust mass surface […]

GOTHAM spectra showcasing several 1-cyanopyrene lines detected in TMC-1 observations. The original GOTHAM observational data for which one channel corresponds to 1.4 kHz were smoothed with a Hanning window to a resolution of 14 kHz, depicted in black. The spectrum of 1-cyanopyrene is overplotted in violet using source-dependent molecular parameters as reported in Table S4. The quantum numbers of each transition, ignoring 14N nuclear electric quadrupole splitting, are reported. Each line contains multiple closely spaced K-components of each transition which are denoted α, β, γ, δ = {0,1}, {1,2}, {2,3}, {3,4}. -- astro-ph.GA

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Interstellar, Sample Return, Status Report

Discovery Of Interstellar 1-cyanopyrene: A Four-ring Polycyclic Aromatic Hydrocarbon In TMC-1

by Keith CowingOctober 5, 2024October 7, 2024

Polycyclic aromatic hydrocarbons (PAHs) are thought to be the most abundant class of molecules in space, yet their interstellar lifecycle is poorly understood due to difficulties detecting individual PAHs.

PAH

Applications of Microbial Bioplastic Polyhydroxyalkanoates as Biosignatures for Astrobiological Detection

A Sensitivity Analysis of the Modeling of Polycyclic Aromatic Hydrocarbon Emission in Galaxies

Battle of the CH Motions: aliphatic vs. Aromatic Contributions to Astronomical PAH Emission and Exploration of the Aliphatic, Aromatic, and Ethynyl CH Stretches

Dust Extinction-curve Variation In The Translucent Interstellar Medium Is Driven By PAH Growth

A Study of Polycyclic Aromatic Hydrocarbon Emission in 30 Dor as seen by JWST

The Largest Molecule Ever Detected Using Radioastronomy

Molecules That Store Carbon Discovered In A Distant Interstellar Cloud

Polycyclic Aromatic Hydrocarbon and CO(2-1) Emission at 50-150 pc Scales in 66 Nearby Galaxies

The Resolved Behavior of Dust Mass, Polycyclic Aromatic Hydrocarbon Fraction, and Radiation Field in ~ 800 Nearby Galaxies

Discovery Of Interstellar 1-cyanopyrene: A Four-ring Polycyclic Aromatic Hydrocarbon In TMC-1

Dragonfly Titan Astrobiology Droid Clears Key Tests

Expedition Led By MBARI Researchers Reveals A Remarkable, And Rare, Form Of Deep-sea Hydrothermal Vents

SwRI Study Found Primordial Mini-moons May Explain Meteorite Composition

The Galactic Centre G+0.633-0.0604 Molecular Cloud: A New Astrochemical Gold Mine. I. Gas Physical Properties

Researchers Confirm The Cause Of Earth’s Biggest Mass Extinction