Work

The Column Density Probability Density Function of Cygnus-X

Year: 2026

Type: article

Abstract: The density distribution within molecular clouds offers critical insights into their underlying physical processes, which are essential for understanding star formation. As a statistical measure of column density on the cloud scale, the shape and evolution of the column density probability density function (N-PDF) serve as important tools for understanding the dynamics between turbulence and gravity. Here, we investigate the N-PDFs of Cygnus-X using the column density map obtained from Herschel, supplemented by H I and young stellar objects data. We find that the N-PDFs of Cygnus-X and four subregions display log-normal + power-law shapes, indicating the combined effects of turbulence and gravity in sculpting the density structure. We find evidence that the power-law segment of the N-PDFs flattens over time, and the transitional column density can be seen as a unique and stable star formation threshold specific to each molecular cloud. These results not only clarify the physical state of Cygnus-X but also emphasize the utility of the N-PDF as a statistical diagnostic tool, as it is an accessible indicator of evolutionary stages and star formation thresholds in molecular clouds.

Source: The Astronomical Journal

DOI: 10.3847/1538-3881/ae331a

Authors: Yuchen Xing, Keping Qiu

Institutions: Chinese Academy of Sciences, National Astronomical Observatories, University of Chinese Academy of Sciences, Nanjing University

Language: English

Topic: Astrophysics and Star Formation Studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funder: National Natural Science Foundation of China