Interstellar Archives

Metallicity calculated over the full lines of sight as a function of distance from the Galactic center plotted for this work compared with literature results. The red diamonds are the results from the fit to abundance patterns for all metals, the green and purple diamonds are fits to the refractory and volatile metals respectively. We do not include the fits for ρ Oph A because of the limited data. The fit to the refractory metals for θ 1 Ori C is 1.7, which we do not consider as physical, so it is excluded in this plot. -- astro-ph.GA

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

Investigating Chemical Variations Between Interstellar Gas Clouds In The Solar Neighbourhood

by Keith CowingJanuary 13, 2025January 12, 2025

The interstellar medium (ISM) is a fundamental component of the Milky Way. Studying its chemical composition and the level of its chemical diversity gives us insight into the evolution of […]

Schematic representation of the overall suggested mechanism. Various polyynes observed in dark clouds (e.g., TMC-1) are presented in the left part of the reaction scheme. The accretion of polyynes on the surface of the grains is followed by hydrogenation of their unsaturated CC triple bonds, resulting in the formation of their semi-saturated and fully saturated counterparts. Besides CH2CHCCCHO, all of the firstgeneration products obtained by such hydrogenation have also been observed in the gas phase in TMC-1 or other dark clouds (Brown 1981; Irvine & Hjalmarson 1984; Agúndez et al. 2021; Cernicharo et al. 2001, 2020, 2021a,b, 2024; Lee et al. 2021; McGuire et al. 2017). In the right part of the reaction scheme, we present the fully saturated aliphatic organic compounds. Most of these molecules have been observed in the comet 67P/Churyumov-Gerasimenko. The heavy molecules whose identifications are still lacking are marked with asterisks. It should be noted that UVphotolysis and cosmic ray processing of fully saturated aliphatic compounds result in their efficient dehydrogenation. The high saturation degree of the detected aliphatic compounds hints at their partial formation through surface hydrogenation mechanisms (Altwegg et al. 2017; Schuhmann et al. 2019; Hänni et al. 2021, 2022, 2023). The image of comet 67P/Churyumov-Gerasimenko is taken by ESA Rosetta on September 2, 2014. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Meteorites & Asteroids, Status Report

Production of Linear Alkanes via the Solid-state Hydrogenation of Interstellar Polyynes

by Keith CowingJanuary 12, 2025January 11, 2025

Highly unsaturated carbon chains, including polyynes, have been detected in many astronomical regions and planetary systems.

Energy diagram for the C2H5 + S reaction. Values in square brackets indicate energies for the same well in the C2H5 + O reaction studied in Vazart et al. (2020). Insets correspond to the structures at the potential wells. We note that the products cy-CH2SCH2 + H and C2H3SH + H are almost isoenergetic. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Intelligence & Language, Interstellar, Status Report

Detection of Thioacetaldehyde (CH3CHS) in TMC-1: Sulfur-oxygen Differentiation Along The Hydrogenation Sequence

by Keith CowingJanuary 11, 2025January 11, 2025

In recent years the chemistry of sulfur in the interstellar medium has experienced a renewed interest due to the detection of a large variety of molecules containing sulfur.

The WISE and VLASS-SE images of J2335-0004. The right panel is the VLASS-SE image. The FWHM and centroid derived from the VLASS-SE image are blue ellipses and dots in all five panels. The four left panels are W1, W2, W3, and W4 band images of the source. The green contours represent 10𝜎, 50𝜎 and 100𝜎 of the noise levels in WISE W1 and W2 images, 3𝜎 and 6𝜎 in W3 and W4 images, and −1𝜎, 10𝜎 and 80𝜎 in the VLASS-SE image. The candidate star’s location is shown as the red stars in all the panels. -- astro-ph.GA

Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Science Fiction, SETI & Technosignatures, Status Report

High-resolution Imaging Of The Radio Source Associated With Project Hephaistos Dyson Sphere Candidate G

by Keith CowingJanuary 11, 2025January 11, 2025

We present high-resolution e-MERLIN and EVN (e-VLBI) observations of a radio source associated with Dyson Sphere candidate G, identified as part of Project Hephaistos.

Schematic illustrating transport mechanisms of volatiles that produce the C/H enhancement seen within the CO snowline in HD 163296 as observed by Zhang et al. (2020). The process begins in the outer disc with dust growing to pebbles as the CO and water vapour freeze out onto the pebbles. As the grains grow, they decouple from the gas and drift inwards towards the CO snowline; within the snowline, the CO sublimates and enhances the C/H ratio of the gas and vapour present; the CO vapour is transported to the upper layers of the disc via diffusion. It also advects inwards, indicated by the grey arrows. Water ice remains on the pebbles and is transported further inward as the pebbles continue to drift toward the water snowline, which is around 1 AU in our model in this paper. Here, water sublimates and becomes readily available for planet formation in the region where terrestrial planets may be forming. Note that the illustrated emission line probe region is specific to CO rotational lines in this context. This schematic was inspired by Fig. 2 of Cuzzi & Zahnle (2004). -- astro-ph.EP

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report

The CO-Fuelled Time Machine: Tracing Birth Conditions and Terrestrial Planet Formation Outcomes in HD 163296 through Pebble Drift-induced CO Enhancements

by Keith CowingJanuary 11, 2025January 11, 2025

The architecture and composition of planetary systems are thought to be strongly influenced by the transport and delivery of dust and volatiles via ices on pebbles during the planet formation […]

Brightness distribution of the 13CO J=2−1 lines integrated over the velocity interval corresponding to the full width at zero intensity of the C18O J=2−1 lines. The contours show levels at 3, 5, 10, and 20 times the root mean square noise level of the image. -- astro-ph.SR

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

ALMA Observations of CO Isotopologues Towards Six Obscured post-AGB Stars

by Keith CowingJanuary 9, 2025January 9, 2025

Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB), when an efficient mass-loss process removes a significant fraction of their initial mass.

Integrated intensity map of the Class I CH3OH maser at 36 GHz obtained with the Yebes 40m telescope toward the Sgr B2 molecular cloud. Black cross indicates the location of G+0.693, where we have conducted our deep spectroscopic surveys with the IRAM 30m and Yebes 40m telescopes. Symbols show the location of the Sgr B2(N), (M) and DS massive star-forming regions. -- astro-ph.GA

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

Chemistry In The Galactic Center

by Keith CowingJanuary 8, 2025January 8, 2025

Gas and dust in the Galactic Center are subjected to energetic processing by intense UV radiation fields, widespread shocks, enhanced rates of cosmic-rays and X-rays, and strong magnetic fields.

An image of a dense, star-rich portion of our galaxy, the Milky Way, taken by the Hubble Space Telescope. -- NASA/ESA/Hubble Heritage Team

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

The Carbon In Our Bodies Probably Left The Galaxy And Came Back On A Cosmic ‘Conveyer Belt’

by Keith CowingJanuary 8, 2025January 8, 2025

Life on Earth could not exist without carbon. But carbon itself could not exist without stars. Nearly all elements except hydrogen and helium — including carbon, oxygen and iron — […]

Molecular structures of the CH2C3N and HC3HCN radicals. -- astro-ph.GA

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

Identification of the Interstellar 1-cyano propargyl Radical (HCCCHCN) in TMC-1

by Keith CowingJanuary 7, 2025January 7, 2025

We report the first detection in interstellar medium of the 1-cyano propargyl radical, HC3HCN. This species is an isomer of the 3-cyano propargyl radical (CH2C3N), which was recently discovered in […]

The spatial coverage of our study of L 1688A, with the underlying extinction map being computed using 2MASS catalog (Cutri et al. 2003) adopting the NICE technique from Lada et al. (1994). The color bar shows the extinction range. The red square encloses the area of the W band observations covering a field of 20′ × 20′ corresponding to a linear scale of 0.8 pc. -- astro-ph.SR

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Brown Dwarfs, Exoplanets, -moons, -comets, Gaia Mission, Icy Worlds, Interstellar, Status Report, Water/Hycean Worlds & Oceanography

Water-Bearing Objects in the Core of the Rho Ophiuchi Cloud Complex

by Keith CowingJanuary 3, 2025January 3, 2025

We present a study of very low-mass stars and brown dwarfs in the rich star-forming core of the Rho Ophiuchi cloud complex. The selection of the sample relies on detecting […]

Interstellar

Investigating Chemical Variations Between Interstellar Gas Clouds In The Solar Neighbourhood

Production of Linear Alkanes via the Solid-state Hydrogenation of Interstellar Polyynes

Detection of Thioacetaldehyde (CH3CHS) in TMC-1: Sulfur-oxygen Differentiation Along The Hydrogenation Sequence

High-resolution Imaging Of The Radio Source Associated With Project Hephaistos Dyson Sphere Candidate G

The CO-Fuelled Time Machine: Tracing Birth Conditions and Terrestrial Planet Formation Outcomes in HD 163296 through Pebble Drift-induced CO Enhancements

ALMA Observations of CO Isotopologues Towards Six Obscured post-AGB Stars

Chemistry In The Galactic Center

The Carbon In Our Bodies Probably Left The Galaxy And Came Back On A Cosmic ‘Conveyer Belt’

Identification of the Interstellar 1-cyano propargyl Radical (HCCCHCN) in TMC-1

Water-Bearing Objects in the Core of the Rho Ophiuchi Cloud Complex

A Martian Horizon Last Monday Afternoon

Habitable-zone Earths At The Detection Frontier: Measured Completeness And False-alarm Rate Of A Transit Pipeline For The PLATO M-dwarf Sample

A Homogeneous Survey Of JWST MIRI Transmission Spectra Of 10 Exoplanets

Retrieving Ocean Glint Reflectance Signatures From Directly Imaged Earth-like Exoplanets

Analytical Platform (Microsampling, Catapulting, Trapping, and LIBS) for the Characterization of Discrete Domains in Samples of Astrochemical Interest