Challenges in probing turbulent and magnetic support in cores: The W43-MM1 protocluster case study
Year: 2026
Type: article
Abstract: Context . Estimating the level of nonthermal support in cores is both challenging yet crucial for constraining the earliest stages of star formation and improving our understanding of the underlying physical processes. Aims . We aim to quantify the kinetic and magnetic support operating within the cores of the high-mass protocluster W43-MM1, and to test the simple assumptions behind the approximated virial theorem, which is used to interpret observations. Methods . We used ALMA 12 m molecular line observations of DCN (3–2), 13 CS (5–4), and CH 3 CN (5 3 –4 3 ) to estimate the kinetic support. The plane-of-sky magnetic field strength ( B POS ) was derived from ALMA 12 m dust-polarization observations using the Davis-Chandrasekhar-Fermi (DCF) method. The B POS estimates were obtained in areas with a diameter of ∼12 500 au (∼2.3″, the three-beam scale of polarimetric observations), which ensures statistically meaningful measurements for the DCF analysis. These values were then extrapolated to core scales (∼2500 au) using the density–field strength relation. Results . We derived kinetic support estimates for 45 cores (21 prestellar and 24 protostellar), of which 21 also have magnetic field support estimates. The velocity dispersions range from 0.34 to 4.48 km s −1 . The three-beam scale B POS values span 1.1–22.5 mG, which extrapolate to 1.1–49.3 mG at the core scale. Using the virial theorem, we find 16 out of the subset of 24 cores with turbulence alone (∼70%) to be stable against gravitational collapse. From the subset of 21 cores with both estimates, ten cores (∼50%) appear to be magnetically supported against gravity when considering magnetic fields alone. Combining both estimates, 18 cores (∼85%) are found with α vir,B > 1. These numbers are unexpectedly high, especially for protostellar cores that are expected to be undergoing collapse. Conclusions . We conclude that the contamination of the measured linewidths by organized motions (of order 1–3 km s −1 and consistent with previous observational studies), together with the omission of surface terms in the observational virial theorem, prevents us from accurately measuring the nonthermal support in cores. This highlights that any simplified framework of a virial analysis can introduce significant biases when assessing the physical support mechanisms within cores.
Source: Astronomy and Astrophysics
Institutions: Centre National de la Recherche Scientifique, Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, University of Concepción, Pontificia Universidad Católica del Perú, National Radio Astronomy Observatory, Atacama Large Millimeter Submillimeter Array, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto Argentino de Radioastronomía, The University of Tokyo, University of St Andrews, Scottish Universities Physics Alliance, University of Florida, Institute of Astronomy and Astrophysics, Academia Sinica, National Institutes of Natural Sciences, National Astronomical Observatory of Japan, Academia Sinica, Institut National de Physique Nucléaire et de Physique des Particules, Institut Néel
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Science Foundation, National Radio Astronomy Observatory, Agence Nationale de la Recherche, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, Agencia Nacional de Investigación y Desarrollo, Science and Technology Facilities Council, Japan Society for the Promotion of Science, National Institutes of Natural Sciences, H2020 European Research Council
Awards: Constraining the Origin of Stellar Masses in Hierarchical Infalling Clouds, Understanding our Galactic ecosystem: From the disk of the Milky Way to the formation sites of stars and planets, Mining the ALMA Archive for Massive Young Stellar Object Accretion Bursts, 補剛材つき板の圧縮強度に関する研究, G5313774521, Investigating Magnetic Fields in High-Mass Pre-stellar Cores using ALMA, G5834573078, G5905308874, MEASUREMENT OF TURBULENCE AND MAGNETIC FIELD IN MASSIVE STAR-FORMING REGIONS, TOWARD A PHYSICALLY-BASED UNDERSTANDING OF STAR CLUSTER FORMATION IN MILKY WAY CLOUDS CUSP OF A DATA-DRIVEN REVOLUTION, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA)
OpenAlex ID: W7171928387