Dust in the Smith Cloud? A UV Investigation into the Smith Cloud's Gas-Phase Abundance Patterns

Fuente: arXiv
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Main Authors: Vazquez, Johanna, Barger, Kathleen, Cashman, Frances, Fox, Andrew, Wakker, Bart, Lockman, Felix, Hill, Alex, Poudel, Suraj, Horton, April, Hernandez, Jaq, Nuss, Matthew, Blake, Alice, Corlies, Lauren, Peeples, Molly
Format: Preprint
Published: 2025
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author Vazquez, Johanna
Barger, Kathleen
Cashman, Frances
Fox, Andrew
Wakker, Bart
Lockman, Felix
Hill, Alex
Poudel, Suraj
Horton, April
Hernandez, Jaq
Nuss, Matthew
Blake, Alice
Corlies, Lauren
Peeples, Molly
author_facet Vazquez, Johanna
Barger, Kathleen
Cashman, Frances
Fox, Andrew
Wakker, Bart
Lockman, Felix
Hill, Alex
Poudel, Suraj
Horton, April
Hernandez, Jaq
Nuss, Matthew
Blake, Alice
Corlies, Lauren
Peeples, Molly
contents The Smith Cloud is a high-velocity cloud (HVC) on its final approach to the Milky Way that shows evidence of interaction with the Galaxy's disk. We investigate the metallicity and gas-phase chemical depletion patterns in this HVC using UV absorption-line observations toward two background QSOs taken with the Hubble Space Telescope (HST)/Cosmic Origin Spectrograph (COS) and H I 21-cm emission-line observations taken with Green Bank Telescope (GBT). We find evidence of silicon gas-phase depletion with [Si/S]$=\,-0.72^{+0.26}_{-0.24}$ and [Si/O]$_{3σ}\,\lesssim\,-0.05$, implying the presence of dust within the Smith Cloud. Because dust is galactic in origin, this HVC could trace the return leg of a Galactic fountain or a dwarf galaxy that passed through the Galactic plane.
format Preprint
id arxiv_https___arxiv_org_abs_2504_21212
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dust in the Smith Cloud? A UV Investigation into the Smith Cloud's Gas-Phase Abundance Patterns
Vazquez, Johanna
Barger, Kathleen
Cashman, Frances
Fox, Andrew
Wakker, Bart
Lockman, Felix
Hill, Alex
Poudel, Suraj
Horton, April
Hernandez, Jaq
Nuss, Matthew
Blake, Alice
Corlies, Lauren
Peeples, Molly
Astrophysics of Galaxies
The Smith Cloud is a high-velocity cloud (HVC) on its final approach to the Milky Way that shows evidence of interaction with the Galaxy's disk. We investigate the metallicity and gas-phase chemical depletion patterns in this HVC using UV absorption-line observations toward two background QSOs taken with the Hubble Space Telescope (HST)/Cosmic Origin Spectrograph (COS) and H I 21-cm emission-line observations taken with Green Bank Telescope (GBT). We find evidence of silicon gas-phase depletion with [Si/S]$=\,-0.72^{+0.26}_{-0.24}$ and [Si/O]$_{3σ}\,\lesssim\,-0.05$, implying the presence of dust within the Smith Cloud. Because dust is galactic in origin, this HVC could trace the return leg of a Galactic fountain or a dwarf galaxy that passed through the Galactic plane.
title Dust in the Smith Cloud? A UV Investigation into the Smith Cloud's Gas-Phase Abundance Patterns
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2504.21212