Unveiling the Formation of the Massive DR21 Ridge

Bonne, Lars; Bontemps, Sylvain; Schneider, N.; Simon, R.; Clarke, S. D.; Csengeri, T.; Chambers, E. T.; Graf, U. U.; Jackson, James M.; Klein, Randolf; Okada, Yoko; Tielens, A. G. G. M.; Tiwari, M.

doi:10.3847/1538-4357/acd536

Cited by 8 publications

(1 citation statement)

References 129 publications

(181 reference statements)

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“…Including calibration, this required a total observing time of 10 h. The antenna temperature was converted to main beam temperature using a forward efficiency η for = 0.97 and a main beam efficiency η mb = 0.65. To improve the data quality and remove scanning effects in the form of stripes, we employed a method based on principal component analysis (PCA) that was also used for the data presented in other FEEDBACK papers (Tiwari et al 2021;Kabanovic et al 2022;Schneider et al 2023;Bonne et al 2023b). The nominal angular resolution of the [C II] and [O I] data is 14.1 and 6 , respectively, but here we convolve the [C II] data cube to an angular resolution of 20 and a spectral binning of 0.5 km s −1 .…”

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confidence: 99%

The SOFIA FEEDBACK [CII] Legacy Survey: Rapid molecular cloud dispersal in RCW 79

Bonne,

Kabanovic,

Schneider

et al. 2023

A&A

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It has long been discussed whether stellar feedback in the form of winds and/or radiation can shred the nascent molecular cloud, thereby controlling the star formation rate. However, directly probing and quantifying the impact of stellar feedback on the neutral gas of the nascent clouds is challenging. We present an investigation of this impact toward the RCW 79 H II region using the ionized carbon line at 158 μm ([C II]) from the FEEDBACK Legacy Survey. We combine this data with information on the dozen ionizing O stars responsible for the evolution of the region, and observe in [C II] for the first time both blue- and redshifted high-velocity gas that reaches velocities of up to 25 km s−1 relative to the bulk emission of the molecular cloud. This high-velocity gas mostly contains neutral gas, and partly forms a fragmented shell, similar to recently found shells in a few Galactic H II regions. However, this shell does not account for all of the observed neutral high-velocity gas. We also find high-velocity gas streaming out of the nascent cloud through holes, and obtain a range of dynamical timescales below 1.0 Myr for the high-velocity gas that is well below the 2.3 ± 0.5 Myr age of the OB cluster. This suggests a different scenario for the evolution of RCW 79, where the high-velocity gas does not solely stem from a spherical expanding bubble, but also from gas recently ablated at the edge of the turbulent molecular cloud into the surrounding interstellar medium through low-pressure holes or chimneys. The resulting mass ejection rate estimate for the cloud is 0.9–3.5 × 10−2 M⊙ yr−1, which leads to short erosion timescales (< 5 Myr) for the nascent molecular cloud. This finding provides direct observational evidence of rapid molecular cloud dispersal.

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confidence: 99%

The SOFIA FEEDBACK [CII] Legacy Survey: Rapid molecular cloud dispersal in RCW 79

Bonne,

Kabanovic,

Schneider

et al. 2023

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A global view on star formation: The GLOSTAR Galactic plane survey

Gong,

Ortiz-León,

Rugel

et al. 2023

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Context. Cygnus X is one of the closest and most active high-mass star-forming regions in our Galaxy, making it one of the best laboratories for studying massive star formation. Aims. We aim to investigate the properties of molecular gas structures on different linear scales with the 4.8 GHz formaldehyde (H2CO) absorption line in Cygnus X. Methods. As part of the GLOSTAR Galactic plane survey, we performed large-scale (7º×3º) simultaneous H2CO (11,0–11,1) spectral line and radio continuum imaging observations toward Cygnus X at λ ~6 cm with the Karl G. Jansky Very Large Array and the Effelsberg 100 m radio telescope. We used auxiliary HI, 13CO (1–0), dust continuum, and dust polarization data for our analysis. Results. Our Effelsberg observations reveal widespread H2CO (11,0–11,1) absorption with a spatial extent of ≳50 pc in Cygnus X for the first time. On large scales of 4.4 pc, the relative orientation between the local velocity gradient and the magnetic field tends to be more parallel at H2 column densities of ≳1.8×1022 cm−2. On the smaller scale of 0.17 pc, our VLA+Effelsberg combined data reveal H2CO (11,0–11,1) absorption only towards three bright HII regions. Our observations demonstrate that H2CO (11,0–11,1) is optically thin in general. The kinematic analysis supports the assertion that molecular clouds generally exhibit supersonic motions on scales of 0.17−4.4 pc. We show a non-negligible contribution of the cosmic microwave background radiation to the extended absorption features in Cygnus X. Our observations suggest that H2CO (11,0–11,1) can trace molecular gas with H2 column densities of ≳5 × 1021 cm−2 (i.e., AV ≳ 5). The ortho-H2CO fractional abundance with respect to H2 has a mean value of 7.0 × 10−10. A comparison of the velocity dispersions on different linear scales suggests that the velocity dispersions of the dominant −3 km s−1 velocity component in the prominent DR21 region are nearly identical on scales of 0.17−4.4 pc, which deviates from the expected behavior of classic turbulence.

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Description of turbulent dynamics in the interstellar medium: Multifractal microcanonical analysis

Rashidi,

Yahia,

Bontemps

et al. 2024

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We present significant improvements to our previous work on noise reduction in Herschel observation maps by defining sparse filtering tools capable of handling, in a unified formalism, a significantly improved noise reduction as well as a deconvolution in order to reduce effects introduced by the limited instrumental response (beam). We implement greater flexibility by allowing a wider choice of parsimonious priors in the noise-reduction process. More precisely, we introduce a sparse filtering and deconvolution approach approach of type $l^2$-$l^p$, with $p > 0$ variable and apply it to a larger set of molecular clouds using Herschel $m data in order to demonstrate their wide range of application. In the Herschel data, we are able to use this approach to highlight extremely fine filamentary structures and obtain singularity spectra that tend to show a significantly less log -normal behavior and a filamentary nature in the less dense regions. We also use high-resolution adaptive magneto-hydrodynamic simulation data to assess the quality of deconvolution in such a simulated beaming framework.

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Unveiling the Formation of the Massive DR21 Ridge

Cited by 8 publications

References 129 publications

The SOFIA FEEDBACK [CII] Legacy Survey: Rapid molecular cloud dispersal in RCW 79

The SOFIA FEEDBACK [CII] Legacy Survey: Rapid molecular cloud dispersal in RCW 79

A global view on star formation: The GLOSTAR Galactic plane survey

Description of turbulent dynamics in the interstellar medium: Multifractal microcanonical analysis

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