| Issue |
A&A
Volume 696, April 2025
|
|
|---|---|---|
| Article Number | L5 | |
| Number of page(s) | 7 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202453040 | |
| Published online | 07 April 2025 | |
Letter to the Editor
External tides: An important driver of velocity dispersion in molecular clouds
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⋆ Corresponding author; jwzhou@mpifr-bonn.mpg.de
Received:
17
November
2024
Accepted:
20
March
2025
Using the 3D density distribution derived from the 3D dust map of the solar neighborhood, the gravitational potential is obtained by solving the Poisson equation and the tidal tensor can then be computed. In optimal decomposition, the external tidal tensor follows the same formalism as that of a point mass. The average tidal strength of the clouds, derived from both tidal tensor analysis and pixel-by-pixel computation, shows consistent results. The equivalent velocity dispersion of the clouds, estimated from the average tidal strength, is comparable in magnitude to the velocity dispersion measured from CO (1–0) line emission. This suggests that tidal effects from surrounding material may play a significant role in driving velocity dispersion within the clouds. Future studies should carefully consider these tidal effects in star-forming regions.
Key words: ISM: clouds / dust, extinction / ISM: kinematics and dynamics / ISM: structure
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model.
Open access funding provided by Max Planck Society.
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