Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

The formation of solar-neighbourhood stars in two generations separated by 5 billion years

Nature volume 559, pages 585–588 (2018)Cite this article

Subjects

Abstract

The chemical compositions of stars encode those of the gas from which they formed, providing important clues regarding the formation histories of galaxies. A powerful diagnostic is the abundance of α elements (O, Mg, Si, S, Ca and Ti) relative to iron, [α/Fe]. The α elements are synthesized and injected into the interstellar medium by type II supernovae, which occur about ten million years after their originating stars form; by contrast, iron is returned to the interstellar medium by type Ia supernovae, which occur after a much longer timescale of roughly one billion years1. Periods of rapid star formation therefore tend to produce high-[α/Fe] stellar populations (because only type II supernovae have time to contribute to interstellar-medium enrichment as the stellar population forms), whereas low-[α/Fe] stars require periods of star formation that last more than a few billion years (over which timescales type Ia supernovae begin to affect the elemental composition of the interstellar medium more strongly than type II supernovae). The existence of two distinct groups of stars in the solar neighbourhood2,3,4,5,6,7, one with high [α/Fe] and the other with low [α/Fe], therefore suggests two different origins, but the mechanism by which this bimodal distribution arose remains unknown. Here we use a model of disk-galaxy evolution to show that the two episodes of star formation8 predicted by the ‘cold flow’ theory of galactic gas accretion9,10 also explain the observed chemical bimodality. In this scenario, the high-[α/Fe] stars form early, during an initial phase of accretion that involves infalling streams of cold primordial gas. There is then a hiatus of around two billion years until the shock-heated gas in the galactic dark-matter halo has cooled as a result of radiation and can itself commence accretion. The low-[α/Fe] stars form during this second phase. The peaks in these two star-formation episodes are separated by around five billion years. In addition, the large-scale variation in the abundance patterns of these two stellar populations that has been observed for the Milky Way5,7 is partially explained by the spatial variation in this gas-accretion history.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Chemical evolution and the chemical abundance diagram for the solar neighbourhood.
Fig. 2: Time of entering the dark-matter halo as a function of arrival time to the disk.
Fig. 3: Evolution of the cold-flow model in three different zones.

Similar content being viewed by others

References

  1. Matteucci, F. & Greggio, L. Relative roles of type I and II supernovae in the chemical enrichment of the interstellar gas. Astron. Astrophys. 154, 279–287 (1986).

    ADS  CAS  Google Scholar 

  2. Gratton, R., Carretta, E., Matteucci, F. & Sneden, C. The [Fe/O] ratio in field stars and the history of star formation of the solar neighbourhood. ASP Conf. Ser. 92, 307–316 (1996).

    ADS  Google Scholar 

  3. Adibekyan, V. Zh. et al. Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program: galactic stellar populations and planets. Astron. Astrophys. 545, A32 (2012).

    Article  CAS  Google Scholar 

  4. Haywood, M. et al. When the Milky Way turned off the lights: APOGEE provides evidence of star formation quenching in our Galaxy. Astron. Astrophys. 589, A66 (2016).

    Article  CAS  Google Scholar 

  5. Anders, F. et al. Chemodynamics of the Milky Way I. The first year of APOGEE data. Astron. Astrophys. 564, A115 (2014).

    Article  CAS  Google Scholar 

  6. Bensby, T., Feltzing, S. & Oey, M. S. Exploring the Milky Way stellar disk: a detailed elemental abundance study of 714 F and G dwarf stars in the solar neighbourhood. Astron. Astrophys. 562, A71 (2014).

    Article  ADS  CAS  Google Scholar 

  7. Hayden, M. R. et al. Chemical cartography with APOGEE: metallicity distribution functions and the chemical structure of the Milky Way disk. Astrophys. J. 808, 132 (2015).

    Article  ADS  CAS  Google Scholar 

  8. Birnboim, Y., Dekel, A. & Neistein, E. Bursting and quenching in massive galaxies without major mergers or AGNs. Mon. Not. R. Astron. Soc. 380, 339–352 (2007).

    Article  ADS  Google Scholar 

  9. Fardal, M. A. et al. Cooling radiation and the Lyα luminosity of forming galaxies. Astrophys. J. 562, 605–617 (2001).

    Article  ADS  CAS  Google Scholar 

  10. Dekel, A. & Birnboim, Y. Galaxy bimodality due to cold flows and shock heating. Mon. Not. R. Astron. Soc. 368, 2–20 (2006).

    Article  ADS  CAS  Google Scholar 

  11. Schönrich, R. & Binney, J. Chemical evolution with radial mixing. Mon. Not. R. Astron. Soc. 396, 203–222 (2009).

    Article  ADS  CAS  Google Scholar 

  12. Chiappini, C., Matteucci, F. & Gratton, R. The chemical evolution of the Galaxy: the two-infall model. Astrophys. J. 477, 765–780 (1997).

    Article  ADS  CAS  Google Scholar 

  13. Snaith, O. et al. Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances. Astron. Astrophys. 578, A87 (2015).

    Article  CAS  Google Scholar 

  14. Rees, M. J. & Ostriker, J. P. Cooling, dynamics and fragmentation of massive gas clouds: clues to the masses and radii of galaxies and clusters. Mon. Not. R. Astron. Soc. 179, 541–559 (1977).

    Article  ADS  CAS  Google Scholar 

  15. Noguchi, M. Possible imprints of cold mode accretion on the present-day properties of disk galaxies. Astrophys. J. 853, 67 (2018).

    Article  ADS  Google Scholar 

  16. Gilmore, G. et al. The Gaia-ESO public spectroscopic survey. Messenger 147, 25–31 (2012).

    ADS  Google Scholar 

  17. Majewski, S. R. et al. The Apache Point Observatory Galactic Evolution Experiment (APOGEE). Astron. J. 154, 94–139 (2017).

    Article  ADS  CAS  Google Scholar 

  18. Mayor, M. et al. Setting new standards with HARPS. Messenger 114, 20–24 (2003).

    ADS  Google Scholar 

  19. Danovich, M., Dekel, A., Hahn, O., Ceverino, D. & Primack, J. Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge. Mon. Not. R. Astron. Soc. 449, 2087–2111 (2015).

    Article  ADS  CAS  Google Scholar 

  20. Romano, D., Karakas, A. I., Tosi, M. & Matteucci, F. Quantifying the uncertainties of chemical evolution studies II. Stellar yields. Astron. Astrophys. 522, A32 (2010).

    Article  ADS  CAS  Google Scholar 

  21. Wyse, R. F. G. & Silk, J. Star formation rates and abundance gradients in disk galaxies. Astrophys. J. 339, 700–711 (1989).

    Article  ADS  CAS  Google Scholar 

  22. Rojas-Arriagada, A. et al. The Gaia-ESO Survey: exploring the complex nature and origins of the Galactic bulge populations. Astron. Astrophys. 601, A140 (2017).

    Article  CAS  Google Scholar 

  23. Haywood, M., Di Matteo, P., Lehnert, M. D., Katz, D. & Gómez, A. The age structure of stellar populations in the solar vicinity: clues of a two-phase formation history of the Milky Way disk. Astron. Astrophys. 560, A109 (2013).

    Article  Google Scholar 

  24. Kobayashi, C. & Nakasato, N. Chemodynamical simulations of the Milky Way galaxy. Astrophys. J. 729, 16 (2011).

    Article  ADS  CAS  Google Scholar 

  25. Williams, B. F. et al. PHAT XIX. The ancient star formation history of the M31 disk. Astrophys. J. 846, 145 (2017).

    Article  ADS  CAS  Google Scholar 

  26. Williams, B. F., Dalcanton, J. J., Dolphin, A. E., Holtzman, J. & Sarajedini, A. The detection of inside-out disk growth in M33. Astrophys. J. 695, L15–L19 (2009).

    Article  ADS  CAS  Google Scholar 

  27. Gogarten, S. M. et al. The Advanced Camera for Surveys Nearby Galaxy Survey Treasury. V. Radial star formation history of NGC 300. Astrophys. J. 712, 858–874 (2010).

    Article  ADS  Google Scholar 

  28. Grand, R. J. J. et al. Origin of chemically distinct discs in the Auriga cosmological simulations. Mon. Not. R. Astron. Soc. 474, 3629–3639 (2018).

    Article  ADS  Google Scholar 

  29. Cattaneo, A., Dekel, A., Devriendt, J., Guiderdoni, B. & Blaizot, J. Modelling the galaxy bimodality: shutdown above a critical halo mass. Mon. Not. R. Astron. Soc. 370, 1651–1665 (2006).

    Article  ADS  CAS  Google Scholar 

  30. Dekel, A. et al. Cold streams in early massive hot haloes as the main mode of galaxy formation. Nature 457, 451–454 (2009).

    Article  ADS  PubMed  CAS  Google Scholar 

  31. Wechsler, R. H., Bullock, J. S., Primack, J. R., Kravtsov, A. V. & Dekel, A. Concentrations of dark halos from their assembly histories. Astrophys. J. 568, 52–70 (2002).

    Article  ADS  CAS  Google Scholar 

  32. Bullock, J. S. et al. Profiles of dark haloes: evolution, scatter and environment. Mon. Not. R. Astron. Soc. 321, 559–575 (2001).

    Article  ADS  Google Scholar 

  33. Ferreras, I. & Silk, J. Type Ia supernovae and the formation history of early-type galaxies. Mon. Not. R. Astron. Soc. 336, 1181–1187 (2002).

    Article  ADS  Google Scholar 

  34. Maoz, D., Sharon, K. & Gal-Yam, A. The supernova delay time distribution in galaxy clusters and implications for type-Ia progenitors and metal enrichment. Astrophys. J. 722, 1879–1894 (2010).

    Article  ADS  Google Scholar 

  35. Claeys, J. S. W., Pols, O. R., Izzard, R. G., Vink, J. & Verbunt, F. W. M. Theoretical uncertainties of the type Ia supernova rate. Astron. Astrophys. 563, A83 (2014).

    Article  ADS  Google Scholar 

  36. Smith, M. C. et al. The RAVE survey: constraining the local Galactic escape speed. Mon. Not. R. Astron. Soc. 379, 755–772 (2007).

    Article  ADS  Google Scholar 

  37. Bovy, J. & Rix, H.-W. A direct dynamical measurement of the Milky Way’s disk surface density profile, disk scale length, and dark matter profile at 4 kpc < r < 9 kpc. Astrophys. J. 779, 115 (2013).

    Article  ADS  Google Scholar 

  38. Licquia, T. C. & Newman, J. A. Improved estimates of the Milky Way’s stellar mass and star formation rate from hierarchical Bayesian meta-analysis. Astrophys. J. 806, 96 (2015).

    Article  ADS  CAS  Google Scholar 

  39. Asplund, M., Grevesse, N., Sauval, A. J. & Scott, P. The chemical composition of the Sun. Annu. Rev. Astron. Astrophys. 47, 481–522 (2009).

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We acknowledge I. Ferreras for comments.

Reviewer information

Nature thanks G. Cescutti, A. Dekel and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information

Authors and Affiliations

  1. Astronomical Institute, Tohoku University, Sendai, Japan

    Masafumi Noguchi

Authors
  1. Masafumi Noguchi
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Masafumi Noguchi.

Ethics declarations

Competing interests

The author declares no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Noguchi, M. The formation of solar-neighbourhood stars in two generations separated by 5 billion years. Nature 559, 585–588 (2018). https://doi.org/10.1038/s41586-018-0329-2

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-018-0329-2

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing