High resolution LAsMA <sup>12</sup>CO and <sup>13</sup>CO observation of the G305 giant molecular cloud complex

Мазумдар, П.; Wyrowski, F.; Urquhart, J. S.; Colombo, D.; Menten, K. M.; Neupane, S.

doi:10.1051/0004-6361/202142036

Cited by 9 publications

(2 citation statements)

References 62 publications

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“…17, the 8 µm surface brightness shows a strong positive correlation with column density for both c-leaves and branch structures, which might be an indication for triggering in the G333 complex. However, branch structures show a more obvious correlation between 8 µm surface brightness and velocity dispersion than c-leaves, which is consistent with the results of Mazumdar et al (2021b), implying that feedback has a greater impact on large-scale structures. The small-scale structures are embedded in large-scale structures, and are therefore less affected by feedback.…”

Section: Feedbacksupporting

confidence: 87%

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex

Zhou,

Wyrowski,

Neupane

et al. 2024

A&A

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Context. Feedback from young massive stars has an important impact on the star formation potential of their parental molecular clouds. Aims. We investigate the physical properties of gas structures under feedback in the G333 complex using data of the 13CO J = 3–2 line observed with the LAsMA heterodyne camera on the APEX telescope. Methods. We used the Dendrogram algorithm to identify molecular gas structures based on the integrated intensity map of the 13CO (3–2) emission, and extracted the average spectra of all structures to investigate their velocity components and gas kinematics. Results. We derive the column density ratios between different transitions of the 13CO emission pixel by pixel, and find the peak values N2−1/N1−0 ≈ 0.5, N3−2/N1−0 ≈ 0.3, and N3−2/N2−1 ≈ 0.5. These ratios can also be roughly predicted by the nonlocal thermodynamic equilibrium (NLTE) molecular radiative transfer code RADEX for an average H2 volume density of ~4.2 × 103 cm−3. A classical virial analysis does not reflect the true physical state of the identified structures, and we find that external pressure from the ambient cloud plays an important role in confining the observed gas structures. For high-column-density structures, velocity dispersion and density show a clear correlation that is not seen for low-column-density structures, indicating the contribution of gravitational collapse to the velocity dispersion. Branch structures show a more significant correlation between 8 μm surface brightness and velocity dispersion than leaf structures, implying that feedback has a greater impact on large-scale structures. For both leaf and branch structures, σ − N * R always has a stronger correlation compared to σ − N and σ − R. The scaling relations are stronger, and have steeper slopes when considering only self-gravitating structures, which are the structures most closely associated with the Heyer relation. Conclusions. Although the feedback disrupting the molecular clouds will break up the original cloud complex, the substructures of the original complex can be reorganized into new gravitationally governed configurations around new gravitational centers. This process is accompanied by structural destruction and generation, and changes in gravitational centers, but gravitational collapse is always ongoing.

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Section: Feedbacksupporting

confidence: 87%

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex

Zhou,

Wyrowski,

Neupane

et al. 2024

A&A

Self Cite

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“…Yet, their expansion locally compresses the gas, enhancing its density and directly impacting the properties of newly forming clumps (Zhang et al 2020(Zhang et al , 2021. These events can affect scales from tens of parsecs down to sub-parsec scales, possibly altering the local star formation properties (Palmeirim et al 2017;Mazumdar et al 2021), or even promoting the formation of other massive stars by inhibiting gas fragmentation (Hennebelle et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Stellar feedback in the star formation–gas density relation: Comparison between simulations and observations

Suin,

Zavagno,

Colman

et al. 2024

A&A

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The impact of stellar feedback on the Kennicutt-Schmidt (KS) law, which relates the star formation rate (SFR) to the surface gas density, is a topic of ongoing debate. The interpretation of high-resolution observations of individual clouds is challenging due to the various processes at play simultaneously and inherent biases. Therefore, a numerical investigation is necessary to understand the role of stellar feedback and identify observable signatures. In this study we investigate the impact of stellar feedback on the KS law, aiming to identify distinct signatures that can be observed and analysed. By employing magnetohydrodynamic simulations of an isolated cloud, we specifically isolate the effects of high-mass star radiation feedback and protostellar jets. High-resolution numerical simulations are a valuable tool for isolating the impact of stellar feedback on the star formation process, while also allowing us to assess how observational biases may affect the derived relation. We used high-resolution (<0.01 pc) magnetohydrodynamic numerical simulations of a 10$^4\ cloud and followed its evolution under different feedback prescriptions. The set of simulations contained four types of feedback: one with only protostellar jets, one with ionising radiation from massive stars (>8 odot $), one with the combination of the two, and one without any stellar feedback. In order to compare these simulations with the existing observational results, we analysed their evolution by adopting the same techniques applied in the observational studies. Then, we simulated how the same analyses would change if the data were affected by typical observational biases: counting young stellar objects (YSO) to estimate the SFR, the limited resolution for the column density maps, and a sensitivity threshold for detecting faint embedded YSOs. Our analysis reveals that the presence of stellar feedback strongly influences the shape of the KS relation and the star formation efficiency per free-fall time (eff ). The impact of feedback on the relation is primarily governed by its influence on the cloud's structure. Additionally, the evolution of eff throughout the star formation event suggests that variations in this quantity can mask the impact of feedback in observational studies that do not account for the evolutionary stage of the clouds. Although the eff measured in our clouds is higher than what is usually observed in real clouds, upon applying prescriptions to mimic observational biases we recover a good agreement with the expected values. From that, we can infer that observations tend to underestimate the total SFR. Moreover, this likely indicates that the physics included in our simulations is sufficient to reproduce the basic mechanisms that contribute to setting eff . We demonstrate the interest of employing numerical simulations to address the impact of early feedback on star formation laws and to correctly interpret observational data. This study will be extended to other types of molecular clouds and ionising stars, sampling different feedback strengths, to fully characterise the impact of regions on star formation.

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Ammonia characterisation of dense cores in the Rosette Molecular Cloud

Bőgner

Csengeri

Montillaud

et al. 2022

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Context. The Rosette molecular cloud complex is a well-known Galactic star-forming region with a morphology pointing towards triggered star formation. The distribution of its young stellar population and the gas properties point to the possibility that star formation is globally triggered in the region. Aims. We focus on the characterisation of the most massive pre-and protostellar cores distributed throughout the molecular cloud in order to understand the star formation processes in the region. Methods. We observed a sample of 33 dense cores, identified in Herschel continuum maps, with the Effelsberg 100-m telescope. Using NH 3 (1,1) and (2,2) measurements, we characterise the dense core population, computing rotational and gas kinetic temperatures and NH 3 column density with multiple methods. We also estimated the gas pressure ratio and virial parameters to examine the stability of the cores. Using results from Herschel data, we examined possible correlations between gas and dust parameters. Results. Ammonia emission is detected towards 31 out of the 33 selected targets. We estimate kinetic temperatures to be between 12 and 20 K, and column densities within the 10 14 − 2 × 10 15 cm −2 range in the selected targets. Our virial analysis suggests that most sources are likely to be gravitationally bound, while the line widths are dominated by non-thermal motions. Our results are compatible with large-scale dust temperature maps suggesting that the temperature decreases and column density increases with distance from NGC 2244 except for the densest protoclusters. We also identify a small spatial shift between the ammonia and dust peaks in the regions most exposed to irradiation from the nearby NGC 2244 stellar cluster. However, we find no trends in terms of core evolution with spatial location, in the prestellar to protostellar core abundance ratio, or the virial parameter. Conclusions. Star formation is more likely based on the primordial structure of the cloud in spite of the impact of irradiation from the nearby cluster, NGC 2244. The physical parameters from the NH 3 measurements suggest gas properties in between those of low-and high-mass star-forming regions, suggesting that the Rosette molecular cloud could host ongoing intermediate-mass star formation, and is unlikely to form high-mass stars.

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High resolution LAsMA ¹²CO and ¹³CO observation of the G305 giant molecular cloud complex

Abstract: The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.

Cited by 9 publications

References 62 publications

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex

Stellar feedback in the star formation–gas density relation: Comparison between simulations and observations

Ammonia characterisation of dense cores in the Rosette Molecular Cloud

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High resolution LAsMA 12CO and 13CO observation of the G305 giant molecular cloud complex

Abstract: The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.

Cited by 9 publications

References 62 publications

High-resolution APEX/LAsMA 12CO and 13CO (3–2) observation of the G333 giant molecular cloud complex

High-resolution APEX/LAsMA 12CO and 13CO (3–2) observation of the G333 giant molecular cloud complex

Stellar feedback in the star formation–gas density relation: Comparison between simulations and observations

Ammonia characterisation of dense cores in the Rosette Molecular Cloud

Contact Info

Product

Resources

About

High resolution LAsMA ¹²CO and ¹³CO observation of the G305 giant molecular cloud complex

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex

High-resolution APEX/LAsMA ¹²CO and ¹³CO (3–2) observation of the G333 giant molecular cloud complex