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HI Self-absorption toward the Cygnus X North: From Atomic Filament to Molecular Filament
- Source :
- The Astrophysical Journal Letters, Volume 948, Number 2, L17 (10 pp), 2023
- Publication Year :
- 2023
-
Abstract
- Using the HI self-absorption data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we perform a study of the cold atomic gas in the Cygnus-X North region. The most remarkable HI cloud is characterized by a filamentary structure, associated in space and in velocity with the principle molecular filament in the Cygnus-X North region. We investigate the transition from the atomic filament to the molecular filament. We find that the HII regions Cygnus OB2 and G081.920+00.138 play a critical role in compressing and shaping the atomic Cygnus-X North filament, where the molecular filament subsequently forms. The cold HI in the DR21 filament has a much larger column density (N(HI) $\sim$ 1 $\times$ 10$^{20}$ cm$^{-2}$) than the theoretical value of the residual atomic gas ($\sim$ 1 $\times$ 10$^{19}$ cm$^{-2}$), suggesting that the HI-to-H$_2$ transition is still in progress. The timescale of the HI-to-H$_2$ transition is estimated to be 3 $\times$ 10$^{5}$ yr, which approximates the ages of massive protostars in the Cygnus-X North region. This implies that the formation of molecular clouds and massive stars may occur almost simultaneously in the DR21 filament, in accord with a picture of rapid and dynamic cloud evolution.<br />Comment: 10 pages, 7 figures
- Subjects :
- Astrophysics - Astrophysics of Galaxies
Subjects
Details
- Database :
- arXiv
- Journal :
- The Astrophysical Journal Letters, Volume 948, Number 2, L17 (10 pp), 2023
- Publication Type :
- Report
- Accession number :
- edsarx.2305.10795
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.3847/2041-8213/accf99