Resolved Dust Emission and CO Isotopologues in Giant Molecular Clouds of the Andromeda Galaxy

2026/02/10 by Chloe Bosomworth, Jan Forbrich, Charles J. Lada +1 · 1 voice
Physics and Astronomy · #Andromeda #Andromeda Galaxy #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Dust lane #Galaxies: Formation, Evolution, Phenomena #Galaxy #Isotopologue #Molecular cloud #Spiral galaxy #Submillimeter Array #astro-ph.GA

paper · pdf · doi:10.3847/1538-4357/ae448b

arxiv published 2026/02/10 · arxiv updated 2026/02/10 · openalex created_date 2026/02/13 · openalex publication_date 2026/03/24 · openalex updated_date 2026/06/11

Abstract

Abstract Dust emission at submillimeter wavelengths can be used to reliably trace the basic properties of molecular clouds. Early results from a recent Submillimeter Array (SMA) survey of the Andromeda galaxy (M31) include the first detections of resolved dust continuum emission from individual giant molecular clouds (GMCs) in an external spiral galaxy. This paper updates the now-complete SMA survey of 80 Herschel-identified giant molecular associations in M31. The SMA survey simultaneously probes dust continuum emission at 230 GHz and the J = 2 → 1 transitions of the CO isotopologues 12 CO, 13 CO, and C 18 O at a spatial resolution of ≲15 pc. Dust continuum emission was detected in 71 cloud cores, of which 26 were resolved. This more than doubles the size of the previous sample. By comparing dust and CO observations with identical astrometry, we directly measure the dust mass-to-light ratios, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>α</mml:mi> <mml:msub> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> <mml:mi mathvariant="normal">CO</mml:mi> </mml:mrow> </mml:msub> </mml:math> , and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>α</mml:mi> <mml:msub> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> <mml:mi mathvariant="normal">CO</mml:mi> </mml:mrow> </mml:msub> </mml:math> . We derive <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&lt;</mml:mo> <mml:mi>α</mml:mi> <mml:msub> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> <mml:mi mathvariant="normal">CO</mml:mi> </mml:mrow> </mml:msub> <mml:mo>&gt;</mml:mo> <mml:mspace width="0.25em"/> <mml:mo>=</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.070</mml:mn> <mml:mspace width="0.25em"/> <mml:mo>±</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.031</mml:mn> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">K</mml:mi> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">pc</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&lt;</mml:mo> <mml:mi>α</mml:mi> <mml:msub> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> <mml:mi mathvariant="normal">CO</mml:mi> </mml:mrow> </mml:msub> <mml:mo>&gt;</mml:mo> <mml:mspace width="0.25em"/> <mml:mo>=</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.37</mml:mn> <mml:mspace width="0.25em"/> <mml:mo>±</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>0.20</mml:mn> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">K</mml:mi> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">pc</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup>

Citations

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Discussions

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