2026-05-06 マサチューセッツ大学アマースト校
A collage featuring four images of spiral galaxies observed by Webb. Blue colours, especially in the centre of the galaxies, are near-infrared light that show the location of bright stars. Orange and yellow show ionised gas and red colours come from complex molecules and dust grains; these are longer mid-infrared wavelengths. They trace out the spiral arms of each galaxy as a network of filaments with cavities in between. Photos credit: ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stockholm University) and the FEAST JWST team.
＜関連情報＞
- https://www.umass.edu/news/article/umass-amherst-astronomer-looks-cradle-where-stars-are-born
- https://www.nature.com/articles/s41550-026-02857-y
若い星団の形成時間スケールは星団の恒星質量によって制御されることが明らかになってきた The emerging timescale of young star clusters regulated by cluster stellar mass
Alex Pedrini,Angela Adamo,Daniela Calzetti,Arjan Bik,Thomas J. Haworth,Bruce G. Elmegreen,Mark R. Krumholz,Sean T. Linden,Benjamin Gregg,Helena Faustino Vieira,Varun Bajaj,Jenna E. Ryon,Ahmad A. Ali,Eric P. Andersson,Giacomo Bortolini,Michele Cignoni,Ana Duarte-Cabral,Kathryn Grasha,Natalia Lahén,Thomas S.-Y. Lai,Drew Lapeer,Matteo Messa,Göran Östlin,Elena Sabbi,… Monica Tosi
Nature Astronomy Published:06 May 2026
DOI:https://doi.org/10.1038/s41550-026-02857-y
Abstract
Quantifying the timescales of star cluster emergence from their natal clouds remains one of the main challenges in understanding the star formation process. These timescales are fundamental measurements of the star formation cycle within galaxies, yet are difficult to constrain due to the complex interplay between stellar feedback and star formation across multiple physical scales. Here we present Hubble Space Telescope and James Webb Space Telescope observations of thousands of young star clusters in four nearby galaxies (M51, M83, NGC 628 and NGC 4449). A substantial fraction of these clusters are still embedded within their natal gas and remain invisible at optical wavelengths. We constrain their emergence process by measuring the timescales required to disperse the surrounding material. We find a strong correlation between dispersal timescale and cluster stellar mass, with massive clusters emerging faster than their lower-mass counterparts. This is a critical constraint on star formation and stellar feedback simulations, which struggle to fully reproduce star clusters formation and emergence. Our results emphasize the central role of massive clusters in driving the escape of ionizing radiation into the galactic medium. Finally, they impose time limitations for planet formation in massive cluster environments where disks get exposed to ultraviolet irradiation and further gas infall is halted.
