A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars

For more than 50 yr, astronomers have mapped the neutral hydrogen gas in the Galaxy assuming kinematically derived distances. We employ the distances of nearby young stars, which trace the gas from which they formed, in longitude–latitude–velocity space to map this gas without using kinematic distan...

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Main Authors: Peter Craig, Sukanya Chakrabarti, Alexander R. Pettitt, Robyn Sanderson, Erik Rosolowsky
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Online Access:https://doi.org/10.3847/1538-4357/ade232
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author Peter Craig
Sukanya Chakrabarti
Alexander R. Pettitt
Robyn Sanderson
Erik Rosolowsky
author_facet Peter Craig
Sukanya Chakrabarti
Alexander R. Pettitt
Robyn Sanderson
Erik Rosolowsky
author_sort Peter Craig
collection DOAJ
description For more than 50 yr, astronomers have mapped the neutral hydrogen gas in the Galaxy assuming kinematically derived distances. We employ the distances of nearby young stars, which trace the gas from which they formed, in longitude–latitude–velocity space to map this gas without using kinematic distances. We denote this new method “pattern matching.” Analysis of simulated spiral galaxies indicates that our pattern matching distances are 24% more accurate than kinematic distances for gas within 15 kpc of the Sun. The two methods provide similar agreement with parallaxes toward these masers, although the kinematic method shows a small systematic offset in distance that is not present in the pattern matching distances. Using parallaxes and velocities for masers, we show that this novel method, when matched with nearby Cepheids, performs well compared to kinematics. This analysis is restricted to sources that have a reasonably good match with a member of our Cepheid sample. The distances derived here, and the associated map, have broad utility—from improving our understanding of star formation and the dynamical structure of the Galaxy, to informing 3D dust maps.
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spelling doaj-art-eec9da03cb1b499881c642aef57b77ca2025-08-20T02:48:17ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988221710.3847/1538-4357/ade232A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young StarsPeter Craig0https://orcid.org/0000-0002-3673-0668Sukanya Chakrabarti1https://orcid.org/0000-0001-6711-8140Alexander R. Pettitt2https://orcid.org/0000-0002-3662-3942Robyn Sanderson3https://orcid.org/0000-0003-3939-3297Erik Rosolowsky4https://orcid.org/0000-0002-5204-2259Center for Data Intensive and Time Domain Astronomy, Michigan State University , East Lansing, MI 48824, USADepartment of Physics and Astronomy, University of Alabama , Huntsville, Huntsville, AL 35899, USADepartment of Physics & Astronomy, California State University , Sacramento, 6000 J Street, Sacramento, CA 95819, USADepartment of Physics and Astronomy, University of Pennsylvania , Philadelphia, PA 19104, USADepartment of Physics, University of Alberta , Edmonton, AB T6G 2E1, CanadaFor more than 50 yr, astronomers have mapped the neutral hydrogen gas in the Galaxy assuming kinematically derived distances. We employ the distances of nearby young stars, which trace the gas from which they formed, in longitude–latitude–velocity space to map this gas without using kinematic distances. We denote this new method “pattern matching.” Analysis of simulated spiral galaxies indicates that our pattern matching distances are 24% more accurate than kinematic distances for gas within 15 kpc of the Sun. The two methods provide similar agreement with parallaxes toward these masers, although the kinematic method shows a small systematic offset in distance that is not present in the pattern matching distances. Using parallaxes and velocities for masers, we show that this novel method, when matched with nearby Cepheids, performs well compared to kinematics. This analysis is restricted to sources that have a reasonably good match with a member of our Cepheid sample. The distances derived here, and the associated map, have broad utility—from improving our understanding of star formation and the dynamical structure of the Galaxy, to informing 3D dust maps.https://doi.org/10.3847/1538-4357/ade232Interstellar mediumMilky Way diskGalaxy structure
spellingShingle Peter Craig
Sukanya Chakrabarti
Alexander R. Pettitt
Robyn Sanderson
Erik Rosolowsky
A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
The Astrophysical Journal
Interstellar medium
Milky Way disk
Galaxy structure
title A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
title_full A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
title_fullStr A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
title_full_unstemmed A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
title_short A Map of the Outer Gas Disk of the Galaxy with Direct Distances from Young Stars
title_sort map of the outer gas disk of the galaxy with direct distances from young stars
topic Interstellar medium
Milky Way disk
Galaxy structure
url https://doi.org/10.3847/1538-4357/ade232
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