TMC-1 Archives

The different views of B3LYP-D3(BJ)/6- 311++G(d,p) level optimized geometric structures for 9- iminofluorene (left) and benzophenone imine (right). The arrow shows C9 position of iminofluorene. -- astro-ph.GA

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

Rotational Spectra And Search For Aromatic Imines: 9-Iminofluorene And Benzophenone Imine

by Keith CowingDecember 26, 2025December 26, 2025

Interstellar detections of several cyano derivatives of large polycyclic aromatic hydrocarbons (PAHs) have now been achieved, enabled by accurate laboratory measurements of their microwave rotational spectra.

Depiction of the reaction network of the C2H4 + CH2CCH+ reaction. The energies are calculated at the DLPNO-CCSD(T)/aug-cc-pvtz level with the ωB97XD/def2-TZVPD harmonic zero point energy. In the diagram EQ are used to refer to the wells (local minima) on the PES, TS refer to transition states, and DC means “Dissociation channels”. This nomenclature is chosen to be consistent with the one provided by the GRRM code (Maeda et al. 2023b). -- astro-ph.GA

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

Ion-molecule Routes Towards Cycles In TMC-1. An Automated Study Of The C2H4 + CH2CCH+ Reaction

by Keith CowingNovember 9, 2025

Cyclopentadiene (c-C5H6) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM).

The NSF Green Bank Telescope. Credit: NSF/AUI/NSF NRAO/J.Hellerman

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

Astrochemistry: The Largest Molecular Survey To-date: GOTHAM Legacy Data Goes Public

by Keith CowingOctober 27, 2025October 27, 2025

A groundbreaking new dataset from the U.S. National Science Foundation Green Bank Telescope (NSF GBT) is now publicly available, opening the door for scientists worldwide to make discoveries in one […]

Figure reproduced from H. Toru Shay et al. (2025). The detected inventory of TMC–1 molecular species and their column densities is converted into numerical vectors with the VICGAE model. The vectorized strings and the corresponding column densities are then used to train a machine learning regressor. Through learning the relationship between vectorized molecular structures and their column densities, the model is optimized to find the best fit. Once trained, the best-fit model can predict column densities for new molecules and be used to identify potential detection targets in TMC–1. -- The Astrophysical Journal

AI - Data - Apps - Cybernetics, Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Bridging Machine Learning and Spectroscopy: A New Analysis for Astrochemical Target Selection

by Keith CowingOctober 27, 2025October 27, 2025

In the last few years, several approaches have used machine learning to reproduce the inventory and column densities of interstellar molecular sources.

Sensitivity analysis of our model to the oxygen atom diffusion energy for CO2 ice (dashed lines) and FA (suming c-t abundances). Values are represented with respect to H2O column density- The difussion Ediff energy is defined from the Ediff/Ebin parameter in our models. Ediff/Ebin is set to 0.25, 0.30 and 0.40 in those models. The pale blue zone represents the observationally constrained abundances of CO2 (Boogert et al. 2015; McClure et al. 2023) and the pale yellow zone represent the same for FA (Boogert et al. 2015; Rocha et al. 2024). We assume that FA and HCOO– abundances sum. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Impact events, Interstellar, Status Report

Piecing Together Formic Acid Isomerism In Dark Clouds. Detection Of Cis-formic Acid In TMC-1 And Astrochemical Modeling

by Keith CowingSeptember 25, 2025

The presence of molecular isomers in interstellar environments has become a topic of growing interest within the astrochemical community.

The structures and relative zero-point-corrected energies (in kJ/mol and kT-equivalent temperature) of the four most stable conformers of 3-hydroxypropanal. The dipole moments are listed as µa/µb/µc. The point group of each conformer is also shown. See text for computational details. The red spheres denote oxygen atoms, the grey spheres are carbon atoms, and the white spheres depict hydrogen atoms. -- astro-ph.GA

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

Rotational Spectroscopy And Tentative Interstellar Detection of 3-Hydroxypropanal (HOCH2CH2CHO)in the G+0.693-0.027 Molecular Cloud

by Keith CowingSeptember 1, 2025September 1, 2025

We synthesized the astrochemically relevant molecule 3-hydroxypropanal (HOCH2CH2CHO) and subsequently measured and analyzed its rotational spectrum in several frequency regions ranging from 130 to 485 GHz.

Fractional abundances of PAHs as a function of the number of carbon atoms 𝑁C. Dotted lines denote the estimated abundance upper limits of large quasi-symmetric PAHs in NGC 7027, and these values warrant cautious interpretation (refer to the contextual discussion). The solid curve shows the theoretical prediction from Draine & Lazarian (1998). For comparative analysis, values or upper limits from previous studies are overplotted. -- astro-ph.GA

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

The Missing Giant: Do FAST Spectroscopic Observations Reveal a Scarcity of Large Polycyclic Aromatic Hydrocarbons in Astronomical Environments?

by Keith CowingAugust 23, 2025August 23, 2025

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.

Portion of the spectra of ortho- (top), meta- (middle), and para- (bottom) deuterated benzonitrile (DBCN) recorded in the 75- 110 GHz range. The experimental spectra are shown in black above the x axis, while the simulated spectra at 300 K (calculated from the rotational parameters) are shown in colors below the x axis. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Status Report

Low D/H Ratio For Benzonitrile In TMC-1: Implication For The Origin Of Polycyclic Aromatic Hydrocarbons In Cold Dark Clouds

by Keith CowingJuly 23, 2025July 23, 2025

Radioastronomical observations have recently discovered PAHs of moderate size (up to 24 carbon atoms) in cold dark clouds, although it is currently unknown whether they are formed in situ through […]

Optimized geometry of cyanocoronene, C24H11CN, in its principal axis system spanned by the vectors a and b. The highly symmetric coronene has 12 identical carbon sites for CN-substitution that all result in the same cyanocoronene. Its permanent electric dipole moment was calculated to be µa = 5.67 D and µb = 0.59 D. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Status Report

Discovery of the 7-ring PAH Cyanocoronene (C24H11CN) in GOTHAM Observations of TMC-1

by Keith CowingApril 10, 2025September 18, 2025

We present the synthesis and laboratory rotational spectroscopy of the 7-ring polycyclic aromatic hydrocarbon (PAH) cyanocoronene (C24H11CN) using a laser-ablation assisted cavity-enhanced Fourier transform microwave spectrometer.

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

The Missing Link of Sulfur Chemistry in TMC-1: The Detection of c-C3H2S from the GOTHAM Survey

by Keith CowingJanuary 14, 2025January 14, 2025

We present the spectroscopic characterization of cyclopropenethione (c-C3H2S) in the laboratory and detect it in space using the Green Bank Telescope (GBT) Observations of TMC-1: Hunting Aromatic Molecules (GOTHAM) survey.

TMC-1

Rotational Spectra And Search For Aromatic Imines: 9-Iminofluorene And Benzophenone Imine

Ion-molecule Routes Towards Cycles In TMC-1. An Automated Study Of The C2H4 + CH2CCH+ Reaction

Astrochemistry: The Largest Molecular Survey To-date: GOTHAM Legacy Data Goes Public

Bridging Machine Learning and Spectroscopy: A New Analysis for Astrochemical Target Selection

Piecing Together Formic Acid Isomerism In Dark Clouds. Detection Of Cis-formic Acid In TMC-1 And Astrochemical Modeling

Rotational Spectroscopy And Tentative Interstellar Detection of 3-Hydroxypropanal (HOCH2CH2CHO)in the G+0.693-0.027 Molecular Cloud

The Missing Giant: Do FAST Spectroscopic Observations Reveal a Scarcity of Large Polycyclic Aromatic Hydrocarbons in Astronomical Environments?

Low D/H Ratio For Benzonitrile In TMC-1: Implication For The Origin Of Polycyclic Aromatic Hydrocarbons In Cold Dark Clouds

Discovery of the 7-ring PAH Cyanocoronene (C24H11CN) in GOTHAM Observations of TMC-1

The Missing Link of Sulfur Chemistry in TMC-1: The Detection of c-C3H2S from the GOTHAM Survey

Direct Dating Of 3.5 Ga Biogenic Carbon In A Microbial Mat Remnant, Singhbhum Craton, India

The VLA and High-Frequency SETI: Expanding The Search for Life

GEMS JWST: HATS(-6 b): A Sub-solar Metallicity Giant Planet With Water, Methane And Ammonia In Its Atmosphere

The Tidal Venus Phenomenon: Demographics and Case Studies

RNA Droplets May Have Helped Start life on Earth