Centrally concentrated star formation in young clusters
Assilkhan A. Mac Low M.-M. Polak B. Abdikamalov E. Cournoyer-Cloutier C. Lewis S.C. Kalambay M. Otebay A. Shukirgaliyev B.
1 January 2026EDP Sciences
Astronomy and Astrophysics
2026#7051 - 16 pp.
The study of star cluster evolution necessitates modeling how their density profiles develop from their natal gas distribution. Observational evidence indicates that many star clusters follow a Plummer-like density profile. However, most studies have focused on the phase after gas ejection, neglecting the influence of gas on early dynamical evolution. We investigate the development of star clusters forming within gas clouds, particularly those with a centrally concentrated gas profile. Simulations were conducted using the Torch framework, integrating the FLASH magnetohydrodynamics code into AMUSE. This permitted detailed modeling of star formation, stellar evolution, stellar dynamics, radiative transfer, and gas magnetohydrodynamics. We study the collapse of centrally concentrated, turbulent spheres with a total mass of 2.5 × 103 M⊙, investigating the effects of varying numerical resolution and star formation scenarios. The free-fall time is shorter at the center than at the edges of the cloud, with a minimum value of 0.55 Myr. The key conclusions from this study are: (1) the final stellar density profile is more centrally concentrated than was analytically predicted, reflecting the role of global gas collapse and feedback; (2) subclusters can initially form even in centrally concentrated gas clouds; (3) gas collapses globally toward the center on the central free-fall timescale, contradicting the assumption in analytical models of local fragmentation and star formation; and (4) the mass of the most massive star formed is directly correlated with the cluster effective radius and inversely correlated with the velocity dispersion, while the duration of star formation correlates with the star formation efficiency.
magnetohydrodynamics (MHD) , open clusters and associations: general , stars: formation
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Department of Astronomy, Columbia University, 538 W 120th St, New York, 10027, NY, United States
Department of Astrophysics, American Museum of Natural History, 200 Central Park W., New York, 10024, NY, United States
Gumarbek Daukeyev Almaty University of Power Engineering and Telecommunications, 126/1 Baytursynuli St., Almaty, 050000, Kazakhstan
Heriot-Watt University Aktobe Campus, K. Zhubanov Aktobe Regional University, 263 Zhubanov Brothers St., Aktobe, 030000, Kazakhstan
Nazarbayev University, Physics Department, 53 Kabanbay Batyr Ave., Astana, 010000, Kazakhstan
Energetic Cosmos Laboratory, Nazarbayev University, 53 Kabanbay Batyr Ave., Astana, 010000, Kazakhstan
Max Planck Institute for Astrophysics, Karl-Schwarzschild-Straße 1, Garching bei München, 85748, Germany
Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, L8S 4M1, ON, Canada
Department of Physics, Drexel University, 3141 Chestnut St., Philadelphia, 19104, PA, United States
Fesenkov Astrophysical Institute, 23 Observatory St., Almaty, 050020, Kazakhstan
Al-Farabi Kazakh National University, 71 Al-Farabi ave., Almaty, 050040, Kazakhstan
Department of Astronomy
Department of Astrophysics
Gumarbek Daukeyev Almaty University of Power Engineering and Telecommunications
Heriot-Watt University Aktobe Campus
Nazarbayev University
Energetic Cosmos Laboratory
Max Planck Institute for Astrophysics
Department of Physics and Astronomy
Department of Physics
Fesenkov Astrophysical Institute
Al-Farabi Kazakh National University
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