Cluster-formation in the Rosette molecular cloud at the junctions of filaments
N. Schneider, T. Csengeri, M. Hennemann, F. Motte, P. Didelon, C. Federrath, S. Bontemps, J. Di Francesco, D. Arzoumanian, V. Minier, Ph. André, T. Hill, A. Zav… 展开作者
N. Schneider, T. Csengeri, M. Hennemann, F. Motte, P. Didelon, C. Federrath, S. Bontemps, J. Di Francesco, D. Arzoumanian, V. Minier, Ph. André, T. Hill, A. Zavagno, Q. Nguyen-Luong, M. Attard, J. -Ph. Bernard, D. Elia, C. Fallscheer, M. Griffin, J. Kirk, R. Klessen, V. Könyves, P. Martin, A. Men'shchikov, P. Palmeirim, N. Peretto, M. Pestalozzi, D. Russeil, S. Sadavoy, T. Sousbie, L. Testi, P. Tremblin, D. Ward-Thompson, G. White
For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models including radiation and gravity show that UV-illumination has little or no impact on the global dynamical evolution of the cloud. The Rosette molecular cloud, irradiated by the NGC2244 cluster, is a template region for triggered star-formation, and we investigated its spatial and density structure by applying a curvelet analysis, a filament-tracing algorithm (DisPerSE), and probability density functions (PDFs) on Herschel column density maps, obtained within the HOBYS key program. The analysis reveals not only the filamentary structure of the cloud but also that all known infrared clusters except one lie at junctions of filaments, as predicted by turbulence simulations. The PDFs of sub-regions in the cloud show systematic differences. The two UV-exposed regions have a double-peaked PDF we interprete as caused by shock compression. The deviations of the PDF from the log-normal shape typically associated with low- and high-mass star-forming regions at Av~3-4m and 8-10m, respectively, are found here within the very same cloud. This shows that there is no fundamental difference in the density structure of low- and high-mass star-forming regions. We conclude that star-formation in Rosette - and probably in high-mass star-forming clouds in general - is not globally triggered by the impact of UV-radiation. Moreover, star formation takes place in filaments that arose from the primordial turbulent structure built up during the formation of the cloud. Clusters form at filament mergers, but star formation can be locally induced in the direct interaction zone between an expanding HII--region and the molecular cloud.
Ram-pressure signatures in the dwarf irregular galaxy SextansB revealed by deep MeerKAT HI observations
Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理研究所）；LIRA, Observatoire de Paris, Université PSL, CNRS（巴黎天文台）；Department of Astronomy, University of Cape Town（开普敦大学天文学系）；Département de physique, Université de Montréal（蒙特利尔大学物理系）；Observatoire d’Astrophysique de l’Université Ouaga I Pr Joseph Ki-Zerbo (ODAUO)（瓦加杜古第一大学约瑟夫·基泽博天体物理观测站）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University（罗兹大学物理与电子学院射电天文技术与技术中心）
Discovery of a rich population of compact hub-filament systems in a single star-forming complex
Physical Research Laboratory（物理研究实验室）；National Astronomical Research Institute of Thailand (Public Organization)（泰国国家天文研究所（公共组织））；Aryabhatta Research Institute of Observational Sciences（阿亚帕塔观测科学研究所）；Indian Institute of Technology Gandhinagar（甘地纳加尔印度理工学院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
On the evolution of irradiated turbulent clouds: A comparative study between modes of triggered star-formation
Here we examine the evolution of irradiated clouds using the Smoothed Particle Hydrodynamics ({ \small SPH}) algorithm coupled with a ray-tracing scheme that calculates the position of the ionisation-front at each timestep. We present results from simulations performed for three choices of { \small IR}-flux spanning the range of fluxes emitted by a typical { \small B}-type star to a cluster of { \small OB}-type stars. The extent of photo-ablation, of course, depends on the strength of the incident flux and a strong flux of { \small IR} severely ablates a { \small MC}. Consequently, the first s…
