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Origins of carbon-enhanced metal-poor stars

Sharma, Mahavir; Theuns, Tom; Frenk, Carlos S.; Cooke, Ryan J.

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Authors

Mahavir Sharma



Abstract

We investigate the nature of carbon-enhanced metal-poor (CEMP) stars in Milky Way (MW) analogues selected from the EAGLE cosmological hydrodynamical simulation. The stellar evolution model in EAGLE includes the physics of enrichment by asymptotic giant branch (AGB) stars, winds from massive stars, and Type Ia and Type II supernovae (SNe). In the simulation, star formation in young MW progenitors is bursty due to efficient stellar feedback, which enables poor metal mixing leading to the formation of CEMP stars with extreme abundance patterns. Two classes of CEMP stars emerge: those mostly enriched by low-metallicity Type II SNe with low Fe yields that drive galactic outflows, and those mostly enriched by AGB stars when a gas-poor galaxy accretes pristine gas. The first class resembles CEMP-no stars with high [C/Fe] and low [C/O], the second class resembles CEMP-s stars overabundant in s-process elements and high values of [C/O]. These two enrichment channels explain several trends seen in data: (i) the increase in the scatter and median of [C/O] at low and decreasing [O/H], (ii) the trend of stars with very low [Fe/H] or [C/H] to be of type CEMP-no and (iii) the reduction in the scatter of [α/Fe] with atomic number in metal-poor stars. In this interpretation, CEMP-no stars were enriched by the stars that enabled galaxies to reionize the Universe.

Citation

Sharma, M., Theuns, T., Frenk, C. S., & Cooke, R. J. (2018). Origins of carbon-enhanced metal-poor stars. Monthly Notices of the Royal Astronomical Society, 473(1), 984-995. https://doi.org/10.1093/mnras/stx2392

Journal Article Type Article
Acceptance Date Sep 12, 2017
Online Publication Date Sep 16, 2017
Publication Date Jan 1, 2018
Deposit Date Jan 25, 2018
Publicly Available Date Jan 25, 2018
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 473
Issue 1
Pages 984-995
DOI https://doi.org/10.1093/mnras/stx2392
Public URL https://durham-repository.worktribe.com/output/1340289

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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