Connecting the dusty dots: dust depletion and extinction of local interstellar clouds

Abstract

Investigating the chemical complexity of the interstellar medium (ISM) is key for understanding its physical nature and evolution. In this work, we study parsec-scale interstellar dust clouds in the neutral ISM of the Milky Way using two different probes: dust depletion and dust extinction. We examine their relationship to investigate the distribution of metals and dust in the Solar neighbourhood, and how they are related to the Local Bubble. We use measurements of dust depletion for individual gas clouds along sight lines of sight towards bright O/B stars within 1.1 kpc of the Sun, derived from UV absorption-line spectra. We combine these with parsec-scale 3D dust extinction density maps out to 1.25 kpc. We assume a correlation between dust depletion and dust extinction density, which we use to imply that the absorption components are spatially associated with the peaks in dust extinction density, and to pinpoint the likely locations of the gas clouds in physical space. We identify peaks in the dust extinction curves, and then associate the stronger peaks with the strongest dust depletion components. Independent distance measurements along the line of sight towards one of our targets, theta1 Ori C, validates our results. In our sample, the minimum distance between clouds that have significantly different chemical properties is ~ 100pc, giving an indication on the physical scale on which chemical mixing remains incomplete in the ISM of the Milky Way. For five of the eight targets, we report dust depletion values for gas clouds associated with the Local Bubble. Additionally, we find a velocity gradient that is consistent with the expansion of the Local Bubble, further supporting our methodology. Overall, we show that it is possible to use complementary information from dust depletion and dust extinction to build more detailed maps of ISM metal and dust distributions.

Accepted for publication in Astronomy & Astrophysics on 24 April 2026. Abstract edited for arXiv. Corrected typos in v2

References in corpus (19)

• Gaia Data Release 3: Summary of the content and survey properties
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• The Structure of the Local Interstellar Medium V: Electron Densities
• Star formation near the Sun is driven by expansion of the Local Bubble
• A parsec-scale Galactic 3D dust map out to 1.25 kpc from the Sun
• Parameters of 220 million stars from Gaia BP/RP spectra
• The search for the origin of the Local Bubble redivivus
• Evolution of the dust-to-metals ratio in high-redshift galaxies probed by GRB-DLAs
• Large Metallicity Variations in the Galactic Interstellar Medium
• METAL: The Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud Hubble program. II. Variations of interstellar depletions and dust-to-gas ratio within the LMC
• Dust depletion of metals from local to distant galaxies I: Peculiar nucleosynthesis effects and grain growth in the ISM
• Dust depletion of of metals from local to distant galaxies II: Cosmic dust-to-metal ratio and dust composition
• HD 62542: Probing the Bare, Dense Core of a Translucent Interstellar Cloud
• The Distribution of Metallicities in the Local Galactic Interstellar Medium
• 3D structure of the Milky Way out to 10 kpc from the Sun. Catalogue of large molecular clouds in the Galactic Plane
• Chemical diversity of gas in distant galaxies: The metal and dust enrichment and variations within absorbing galaxies
• Investigating chemical variations between interstellar gas clouds in the Solar neighbourhood