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Modeling Massive Star Embeddedness in the Andromeda Galaxy

Presentation #105.16 in the session Molecular Clouds and the ISM — iPoster Session.

Published onJun 29, 2022
Modeling Massive Star Embeddedness in the Andromeda Galaxy

Massive stars (M >8 M☉) interact with their surrounding interstellar medium (ISM) via dynamically disruptive stellar winds while, over time, migrating away from their natal birth clouds. Both effects reduce the line-of-sight extinction towards massive stars, but the implications for how well massive stars trace the ISM differ for each effect. If massive stars remain embedded in their molecular clouds but form cavities via stellar winds, their proper motions should remain analogous to the ISM. However, if massive stars migrate far away from their molecular birth clouds, this would indicate that their proper motions are not well correlated. In reality, both effects are simultaneous at play, and so by modeling the 3D distribution of the ISM, we hope to constrain how each effect alters the overall distribution of embeddedness.

Utilizing results from the Panchromatic Hubble Andromeda Treasury, we estimate the relative embeddedness of over 33 thousand candidate massive stars in the Andromeda Galaxy (M31) by comparing stellar line-of-sight and regional (25 pc resolution) extinction measurements. We attempt to reproduce the resultant distribution of relative embeddedness by modeling the ISM as a 3D dust probability distribution tracing the scale length and scale height of M31’s thin disk. By varying the prevalence and density of molecular clouds and the migration of massive stars, we are able to characterize how different features of the ISM influence the embeddedness distribution.

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