Infall of gas as the formation mechanism of stars up to 20 times more massive than the Sun

Abstract

Theory predicts and observations confirm that low-mass stars (like the Sun) in their early life grow by accreting gas from the surrounding material. But for stars 10 times more massive than the Sun (10M), the powerful stellar radiation is expected to inhibit accretion1 and thus limit the growth of their mass. Clearly, stars with masses >10M exist, so there must be a way for them to form. The problem may be solved by non-spherical accretion2,3, which allows some of the stellar photons to escape along the symmetry axis where the density is lower. The recent detection of rotating disks5,4,6 and toroids7 around very young massive stars has lent support to the idea that high-mass (8M) stars could form in this way. Here we report observations of an ammonia line towards a high-mass star forming region. We conclude that the gas is falling inwards towards a very young star of 20M, in line with theoretical predictions of non-spherical accretion.

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Figure 1: Absorption and emission by molecular gas towards the hypercompact H ii region G24 A1.
Figure 2: Velocity field in the massive toroid G24 A1.

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Acknowledgements

NRAO is operated by Associated University, Inc., under contract with the National Science Foundation. We thank P. Ho for suggestions that improved the presentation of our results.

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Correspondence to Maria T. Beltrán.

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Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

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Supplementary Notes

This file provides a detailed derivation of the mass accretion rate and a discussion on the uncertainty of the value, and additional references. (PDF 50 kb)

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Beltrán, M., Cesaroni, R., Codella, C. et al. Infall of gas as the formation mechanism of stars up to 20 times more massive than the Sun. Nature 443, 427–429 (2006). https://doi.org/10.1038/nature05074

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