Ubiquitous velocity fluctuations throughout the molecular interstellar medium
Journal article, 2020

The density structure of the interstellar medium determines where stars form and release energy, momentum and heavy elements, driving galaxy evolution1–4. Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scales and galactic environments5. Although dense star-forming gas probably emerges from a combination of instabilities6,7, convergent flows8 and turbulence9, establishing the precise origin is challenging because it requires gas motion to be quantified over many orders of magnitude in spatial scale. Here we measure10–12 the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations that span a spatial dynamic range 10−1–103 pc. We detect ubiquitous velocity fluctuations across all spatial scales and galactic environments. Statistical analysis of these fluctuations indicates how star-forming gas is assembled. We discover oscillatory gas flows with wavelengths ranging from 0.3–400 pc. These flows are coupled to regularly spaced density enhancements that probably form via gravitational instabilities13,14. We also identify stochastic and scale-free velocity and density fluctuations, consistent with the structure generated in turbulent flows9. Our results demonstrate that the structure of the interstellar medium cannot be considered in isolation. Instead, its formation and evolution are controlled by nested, interdependent flows of matter covering many orders of magnitude in spatial scale.

Author

Jonathan D. Henshaw

Max Planck Society

J. M. D. Kruijssen

Astronomisches Rechen-Institut Heidelberg

S. Longmore

Liverpool John Moores University

Manuel Riener

Max Planck Society

Adam K. Leroy

Ohio State University

E. Rosolowsky

University of Alberta

A. Ginsburg

University of Florida

C. Battersby

University of Connecticut

Mélanie Chevance

Astronomisches Rechen-Institut Heidelberg

Sharon E. Meidt

Ghent university

S. C.O. Glover

Heidelberg University

A. Hughes

Institut de Recherche en Astrophysique et Planétologie (IRAP)

Universite Paul Sabatier Toulouse III

Jouni Kainulainen

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

R. S. Klessen

Heidelberg University

E. Schinnerer

Max Planck Society

Andreas Schruba

Max Planck Society

H. Beuther

Max Planck Society

F. Bigiell

University of Bonn

Guillermo A. Blanc

Carnegie Observatories

University of Chile (UCH)

Eric Emsellem

European Southern Observatory (ESO)

CRAL Le Centre de Recherche Astronomique de Lyon

T. Henning

Max Planck Society

Cynthia N. Herrera

Institut de Radioastronomie Millimétrique (IRAM)

Eric W. Koch

University of Alberta

J. Pety

Institut de Radioastronomie Millimétrique (IRAM)

Paris Observatory

S. E. Ragan

Cardiff University

Jiayi Sun

Ohio State University

Nature Astronomy

23973366 (eISSN)

Vol. 4 1064-1071

Subject Categories

Astronomy, Astrophysics and Cosmology

Fluid Mechanics and Acoustics

Fusion, Plasma and Space Physics

DOI

10.1038/s41550-020-1126-z

More information

Latest update

11/5/2020