Hostname: page-component-76fb5796d-dfsvx Total loading time: 0 Render date: 2024-04-25T12:09:51.431Z Has data issue: false hasContentIssue false

New insights on the origin of multiple stellar populations in globular clusters

Published online by Cambridge University Press:  02 August 2018

Jaeyeon Kim
Affiliation:
Center for Galaxy Evolution Research & Department of Astronomy, Yonsei University, Seoul, Korea email: jaeyeonkim93@gmail.com, ywlee2@yonsei.ac.kr
Young-Wook Lee
Affiliation:
Center for Galaxy Evolution Research & Department of Astronomy, Yonsei University, Seoul, Korea email: jaeyeonkim93@gmail.com, ywlee2@yonsei.ac.kr
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters (GCs). Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars (WMS), together with the winds and ejecta from low and intermediate mass asymptotic-giant-branch stars (AGBs), are all locally retained in these less massive systems. We find that the observed Na-O anti-correlations in metal-poor GCs can be reproduced, when multiple episodes of starbursts are allowed to continue in these subsystems. A specific form of star formation history (SFH) with decreasing time intervals between the stellar generations, however, is required to obtain this result, which is in good agreement with the parameters obtained from our stellar evolution models for the horizontal-branch. The “mass budget problem” is also much alleviated by our models without ad-hoc assumptions on star formation efficiency (SFE) and initial mass function (IMF). We also applied these models to investigate the origin of super-helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the WMS can naturally reproduce the required helium enhancement (ΔYZ = 6) for the second generation stars. Disruption of proto-GCs in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2018 

References

Carretta, E., Bragaglia, A., Gratton, R., & Lucatello, S., 2009a, A&A, 505, 139Google Scholar
Carretta, E., Bragaglia, A., Gratton, R. G., et al., 2009b, A&A, 505, 117Google Scholar
Johnson, C. I., Rich, R. M., Kobayashi, C., & Fulbright, J. P., 2012, ApJ, 749, 175Google Scholar
Joo, S.-J., Lee, Y.-W., & Chung, C., 2017, ApJ, 840, 98Google Scholar
Lecureur, A., Hill, V., Zoccali, M., et al., 2007, A&A, 465, 799Google Scholar
Lee, Y. W., Joo, S. J., & Chung, C., 2015, MNRAS, 453, 3906Google Scholar
Lee, Y.-W. & Jang, S., 2016, ApJ, 833, 236Google Scholar
Maeder, A., 1992, A&A, 264, 105Google Scholar
Meynet, G, 2008, EAS Publications Series, 32, 187Google Scholar
Schiavon, R. P., Zamora, O., Carrera, R., et al., 2017, MNRAS, 465, 501Google Scholar
Silich, S. & Tenorio-Tagle, G., 2017, MNRAS, 465, 1375Google Scholar
Tenorio-Tagle, G., Muñoz-Tuñón, C., Silich, S., & Cassisi, S., 2015, ApJ, 814, L8Google Scholar