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Chemical and stellar properties of early-type dwarf galaxies around the Milky Way

Nature Astronomy volume 6, pages 911–922 (2022)Cite this article

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Abstract

Early-type dwarf galaxies (ETDs) are the end-points of the evolution of low-mass galaxies whose gas supplies have been extinguished. The cessation of star formation lays bare the ancient stellar populations. A wealth of information is stored in the colours, magnitudes, metallicities and abundances of resolved stars of the dwarf spheroidal and ultrafaint galaxies around the Milky Way, allowing their chemistry and stellar populations to be studied in great detail. Here we summarize our current understanding, which has advanced rapidly over the past decade owing to flourishing large-scale astrometric, photometric and spectroscopic surveys. We emphasize that the primeval stellar populations in ETDs provide a unique laboratory for studying the physical conditions on small scales at epochs beyond redshift z = 2. We also highlight the observed diversity of star-formation and chemical-enrichment histories in nearby dwarfs. These data cannot yet be fully deciphered to reveal the key processes in dwarf evolution, but the first successful attempts to pin down the sites of heavy-element production have been made.

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Fig. 1: The size–luminosity relation for Milky Way satellites.
Fig. 2: The (stellar) mass–metallicity relation for Milky Way satellites.
Fig. 3: Dwarf galaxy sequences in stellar chemical abundance space.

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Acknowledgements

We thank A. Kravtsov, Á. Skúladóttir and H. Reggiani for kindly providing the data used in Figs. 1–3, and M. Walker and M. Irwin for helpful comments.

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  1. Institute of Astronomy, University of Cambridge, Cambridge, UK

    Vasily Belokurov & N. Wyn Evans

  2. Center for Computational Astrophysics, Flatiron Institute, New York, NY, USA

    Vasily Belokurov

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V.B. and N.W.E. mapped out the scope of the review and edited the manuscript. V.B. provided the first draft of the introduction and ‘Nucleosynthetic trends’ section, collected the data and plotted Figs. 1–3. N.W.E. wrote the first draft of the ‘Generic trends in the Milky Way ETDs’ section and conclusions. Both authors revised the manuscript.

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Correspondence to Vasily Belokurov or N. Wyn Evans.

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Nature Astronomy thanks Evan Kirby, Alex Ji and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Belokurov, V., Evans, N.W. Chemical and stellar properties of early-type dwarf galaxies around the Milky Way. Nat Astron 6, 911–922 (2022). https://doi.org/10.1038/s41550-022-01740-w

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