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EPoS |
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EPoS Contribution
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The SQUALO ALMA project: clump-fed accretion mechanism in high-mass star-forming objects
Alessio Traficante IAPS-INAF, Rome, IT | |
| The formation mechanism of the most massive stars is far from completely understood. It is still unclear if the formation is core-fed or clump-fed, i.e. if the process is an extension of what happens in low-mass stars, or if the process is more dynamical such as a continuous, multiscale accretion from the gas at parsec (or even larger) scales. In this context I will present the results obtained from the 1.3 mm continuum data of the SQUALO (Star formation in QUiescent And Luminous Objects) project. SQUALO is an ALMA survey designed to investigate the properties of 13 massive clumps selected at various evolutionary stages and with the common feature that they all show evidence for accretion at the clump scale. Our observations identify 55 fragments with masses in the range 0.4 ≤ M ≤ 309 Msun, with evidence that the youngest clumps already present some degree of fragmentation. The data show that physical properties such as mass and surface density of the fragments and their parent clumps are tightly correlated. Quite interestingly, the minimum distance between fragments decreases with evolution, suggest a scenario in which massive clumps first fragment under the influence of non-thermal motions driven by the competition between turbulence and gravity. With time gravitational collapse takes over and the fragments organize themselves into more thermally supported objects while continuing to accrete from their parent clump. Overall, our results support a dynamical, clump-fed scenario in which the properties of the parent clumps at the parsec scales strongly influence the formation history of the inner fragments identified with a resolution of few thousands of AU. | |
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| Caption: One example of the ALMA 1.3 continuum image of a clump observed in the SQUALO survey. The green ellipses are the Hi-GAL 160 μm and 250 μm footprints. The blue crosses are the centroids of the fragments considered in the scientific analysis. | |
| Collaborators: B. M. Jones, UKöln, DE A. Avison, SKA Obs, UK G. A. Fuller, UManchester, UK M. Benedettini, IAPS-INAF, IT D. Elia, IAPS-INAF, IT S. Molinari, IAPS-INAF, IT N. Peretto, UCardiff, UK S. Pezzuto, IAPS-INAF, IT T. Pillai, UBoston, US K. L. J. Rygl, IRA-INAF, IT E. Schisano, IAPS-INAF, IT R. J. Smith, UManchester, UK |
Key publication
Relevant topic(s): Collapse Fragmentation High-Mass SF |
| Relevant Big Question: Which is the dominant mechanism that regulates the collapse and the fragmentation of massive regions in our Galaxy? | |