Astrochemistry

Investigating Chemical Variations Between Interstellar Gas Clouds In The Solar Neighbourhood

By Keith Cowing

Status Report

astro-ph.GA

January 13, 2025

Filed under astro-ph.GA, astrochemistry, astronomy, Hubble, Interstellar, interstellar medium, metallicity, Spectroscopy

Investigating Chemical Variations Between Interstellar Gas Clouds In The Solar Neighbourhood — 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

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 the Milky Way and the role of gas in the Galactic environment.

In this paper, we use a novel simulation technique to model the distribution of total hydrogen between gas components, and therefore derive new constraints on the dust depletion and metallicity. We study individual gas components along the lines of sight towards eight bright O/B stars within 1.1 kpc of the Sun using high-resolution HST/STIS absorption spectra (R sim 114 000).

We measure the level of dust depletion for these individual components and find components with higher levels of dust depletion compared to Milky Way sightlines in the literature. We find large ranges in the level of dust depletion among components along lines of sight, up to 1.19 dex.

Although it is not possible to directly measure the metallicity of individual components due to the saturated and damped Ly-alpha line, we investigate possible metallicity ranges for individual gas components by exploring many different distributions of the total hydrogen gas between components.

We select possible combinations of these gas fractions which produce the minimum metallicity difference between components, and for these cases we determine individual metallicities to accuracies that range between sim 0.1 to 0.4 dex.

This work shows that full line-of-sight analyses wash out the level of diversity along lines of sight, and that component-by-component studies give a more in-depth understanding of the chemical intricacies of the interstellar medium.

T. Ramburuth-Hurt, A. De Cia, J.-K. Krogager, C. Ledoux, E. Jenkins, A. J. Fox, C. Konstantopoulou, A. Velichko, L. Dalla Pola

Comments: Re-submitted to Astronomy & Astrophysics after positive feedback from the referee. Abstract edited for arXiv
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2412.18986 [astro-ph.GA] (or arXiv:2412.18986v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2412.18986
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Submission history
From: Tanita Ramburuth-Hurt
[v1] Wed, 25 Dec 2024 21:47:46 UTC (8,732 KB)
https://arxiv.org/abs/2412.18986
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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