interstellar medium Archives

This image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) of star-forming region NGC 604 shows how stellar winds from bright, hot, young stars carve out cavities in surrounding gas and dust. NASA, ESA, CSA, STScI

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

Astrochemistry: Peering Into The Tendrils Of NGC 604 With Webb Space Telescope

by Keith CowingMarch 12, 2024March 12, 2024

The formation of stars and the chaotic environments they inhabit is one of the most well-studied, but also mystery-shrouded, areas of cosmic investigation. The intricacies of these processes are now […]

Top left panel (a): Comparison of the UV absorption of indene with an elevated value at λ < 0.19 µm (“higher Cabs”; black long-dashed line) and that with the absorption at λ < 0.19 µm extrapolated from that at λ > 0.19 µm (“lower Cabs”; magenta dashed line). The UV absorption at λ > 0.19 µm for both cases is the same as Figure 1. Bottom left panel (b): Comparison of the MMP83 interstellar radiation field (red) with the radiation fields represented by different stellar effective temperatures (Teff = 40, 000 K: blue; Teff = 22, 000 K: cyan; and Teff = 8, 000 K: green). All the radiation intensities are normalized at λ = 0.2 µm. Right panel (c): Comparison of the model IR emission spectrum of indene in the diffuse ISM calculated with an elevated UV absorption at λ < 0.19 µm (dashed blue line) and that with the extrapolated UV absorption at λ < 0.19 µm (solid red line). -- astro-ph.GA

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

Infrared Emission of Specific Polycyclic Aromatic Hydrocarbon Molecules: Indene

by Keith CowingMarch 12, 2024March 12, 2024

Polycyclic aromatic hydrocarbon (PAH) molecules have long been suggested to be present in the interstellar medium (ISM). Nevertheless, despite their expected ubiquity and sustained searching efforts, identifying specific interstellar PAH […]

Overview of reported 14N/ 15N ratios in HCN at various evolutionary stages from cores to disks. The majority of the measurements for HCN are derived using the indirect double isotope method; hence, a fixed 12C/ 13C ratio of 68 is assumed. Protoplanetary disks are abbreviated to PPDs in the figure. References are provided in Appendix A. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Interstellar, Status Report

Fractionation In Young Cores: Direct Determinations Of Nitrogen And Carbon Fractionation In HCN

by Keith CowingMarch 9, 2024March 9, 2024

We aim to determine the 14N/15N and 12C/13C ratios for HCN in six starless and prestellar cores and compare the results between the direct method using radiative transfer modeling and […]

Two-state formation channels for acetamide, N-methyl-formamide (NMF), and acetimidic acid. Two Cchannels are active, while the N2-channel leading to NMF are blocked by an energy barrier. -- chemrxiv.org

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Interstellar, Status Report

Spin-Forbidden Formation of Amide Molecules in the Interstellar Medium

by Keith CowingFebruary 27, 2024February 27, 2024

In this study, two-state spin-forbidden mechanisms are proposed for the barrierless formation of amide isomers in the C2H5NO family of molecules. This family belongs to the first level of complexity […]

An interstellar dust grain: a chemical factory. Schematic representation of its composition and reactivity. -- ACS Cent. Sci.

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Origin & Evolution of Life, Status Report

Interstellar Ices: A Factory of the Origin-of-Life Molecules

by Keith CowingFebruary 12, 2024February 11, 2024

In the past few years, molecular discovery in space has made tremendous progress in terms of both the number of identified molecules and their complexity.

Potential energy surface scan of the NH2CHCO conformer proposed by Krasnokutski (2021); Krasnokutski et al. (2022) at the CCSD(T)- F12/cc-pCVTZ-F12 level of theory. Resolution is of two degrees. Dihedral values refer to the angles lying between the hydrogen of the primary amine and the CN bond. -- astro-ph.GA

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

Accurate Ab Initio Spectroscopic Studies Of Promising Interstellar Ethanolamine Iminic Precursors

by Keith CowingJanuary 26, 2024

Context. The detection of NH2CH2CH2OH (ethanolamine) in molecular cloud G+0.693-0.027 adds an additional player to the prebiotic molecules discovered so far in the interstellar medium (ISM). As this molecule might […]

Continuum emission image of G31.41+0.31 at a frequency 99.915 GHz (3.02 mm). The blue circle represents the synthesized beam size of 1.30′′× 1.02′′. The contour levels begin at 3σ (σ = 3.36 mJy, the root mean square of the background of the continuum emission image) and increase by the factor of √ 2. -- astro-ph.GA

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

Detection And Chemical Modelling Of Complex Prebiotic Molecule Cyanamide In The Hot Molecular Core G31.41+0.31

by Keith CowingJanuary 25, 2024January 24, 2024

In the interstellar medium (ISM), the complex prebiotic molecule cyanamide (NH2CN) plays a key role in producing adenine (C5H5N5), purines (C5H4N4), pyrimidines (C4H4N2), and other biomolecules via a series of […]

UVIT and JWST images of the sample of galaxies are shown in the top and bottom panels. The field of JWST observation is marked in the UVIT FUV images. The UVIT footprint with JWST observation and the corresponding JWST color composite image of the sample of galaxies are shown in the bottom panel. The JWST color composite images are generated using F770W, F1130W, and F2100W filters, which are color-coded in blue, green, and red, respectively. Blue ellipses in the UVIT footprints in the lower panel represents the PAH bright regions identified using ProFound. For all the images North is up and East to the left. -- astro-ph.GA

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

Disentangling The Association Of PAH Molecules With Star Formation : Insights From JWST And UVIT

by Keith CowingJanuary 11, 2024January 10, 2024

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous complex molecules in the interstellar medium and are used as an indirect indicator of star-formation.

IR difference spectra obtained upon irradiation of a similar incident energy with 2 keV electrons of CO:15N2:H2 ice samples in Experiments 4−6. The IR difference spectra were baseline-corrected using a spline function with the IDL software. IR band assignments are indicated in the panels. Tentative assignments are indicated in grey. Grey asterisks indicate possible baseline artifacts that were not subtracted. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Interstellar, Status Report

Organic Chemistry In The H2-bearing, CO-rich Interstellar Ice Layer At Temperatures Relevant To Dense Cloud Interiors

by Keith CowingJanuary 11, 2024January 10, 2024

Ice chemistry in the dense, cold interstellar medium (ISM) is probably responsible for the formation of interstellar complex organic molecules (COMs).

Overview of the d203-506 externally irradiated protoplanetary disk. Integrated intensity images from NIRCam F212N filter (a), Hubble Space Telescope [OI] (b), NIRSpec [FeII] (c), NIRSpec CH+ 1-0 P(7) at 3.95 µm (d), and MIRI MRS integrated from 7.16 to 7.20 µm assigned to CH+ 3 (e). Each panel is centered at α=5:35:20.318 and δ=-5:25:05.662 and are 2" × 2" wide. Contours of NIRCam vibrationally excited H2 (2.12 µm band) are represented in orange, and ALMA dust continuum emission at 344 GHz from the disk in white contours. (f,) Sketch of the d203-506 disk, jet, and wind. We note that the low mass star is not seen in the images because of the disk flaring. All JWST images are from the PDRs4All program, while the Hubble image is from (9). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Interstellar, Status Report

Formation Of The Methyl Cation By Photochemistry In A Protoplanetary Disk

by Keith CowingJanuary 10, 2024January 10, 2024

Forty years ago it was proposed that gas phase organic chemistry in the interstellar medium was initiated by the methyl cation CH3+, but hitherto it has not been observed outside […]