Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams

K. B. Webber; T. T. Hansen; J. L. Marshall; Alexander P. Ji; Ting S. Li; Gary S. Da Costa; Lara R. Cullinane; Denis Erkal; Sergey E. Koposov; Kyler Kuehn; Geraint F. Lewis; Dougal Mackey; Sarah L. Martell; Andrew B. Pace; Nora Shipp; Jeffrey D. Simpson; Zhen Wan; Daniel B. Zucker; Victor A. Alvarado; Joss Bland-Hawthorn; Guilherme Limberg; Gustavo E. Medina; Sam A. Usman

doi:10.3847/1538-4357/ae2d59

Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams

K. B. Webber^*
, T. T. Hansen
, J. L. Marshall
, Alexander P. Ji
, Ting S. Li
, Gary S. Da Costa
, Lara R. Cullinane
, Denis Erkal
, Sergey E. Koposov
, Kyler Kuehn
, Geraint F. Lewis
, Dougal Mackey
, Sarah L. Martell
, Andrew B. Pace
, Nora Shipp
, Jeffrey D. Simpson
, Zhen Wan
, Daniel B. Zucker
, Victor A. Alvarado
, Joss Bland-Hawthorn

Guilherme Limberg, Gustavo E. Medina, Sam A. Usman

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/MIKE spectra. Abundances for 27 elements, ranging from carbon to dysprosium, were derived. Our results support the original classification that
Turranburra, with a low average metallicity of [Fe/H] = −2.45 ± 0.07, likely originates from a dwarf-galaxy progenitor. Willka Yaku has a low average metallicity of [Fe/H] = −2.35 ± 0.03 with a small scatter in the abundances, consistent with a globular cluster progenitor as suggested by previous studies. Both streams exhibit mild enhancements in neutron-capture elements, with averages of [EuII/Fe] = 0.47 ± 0.09 for Turranburra
and 0.44 ± 0.05 for Willka Yaku, consistent with enrichment from an r-process event. A similar enrichment is observed in other stellar streams, and we further discuss this signature as it relates to the potential enrichment histories of these two streams.

Original language	English
Article number	114
Pages (from-to)	1-19
Number of pages	19
Journal	Astrophysical Journal
Volume	998
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ae2d59
Publication status	Published - 5 Feb 2026

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https://arxiv.org/abs/2512.10003Licence: Creative Commons: Attribution (CC-BY)

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Webber, K. B., Hansen, T. T., Marshall, J. L., Ji, A. P., Li, T. S., Costa, G. S. D., Cullinane, L. R., Erkal, D., Koposov, S. E., Kuehn, K., Lewis, G. F., Mackey, D., Martell, S. L., Pace, A. B., Shipp, N., Simpson, J. D., Wan, Z., Zucker, D. B., Alvarado, V. A., ... Usman, S. A. (2026). Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams. Astrophysical Journal, 998(1), 1-19. Article 114. https://doi.org/10.3847/1538-4357/ae2d59

@article{b678b4759534458094f7def872f6091a,

title = "Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams",

abstract = "We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/MIKE spectra. Abundances for 27 elements, ranging from carbon to dysprosium, were derived. Our results support the original classification that Turranburra, with a low average metallicity of [Fe/H] = −2.45 ± 0.07, likely originates from a dwarf-galaxy progenitor. Willka Yaku has a low average metallicity of [Fe/H] = −2.35 ± 0.03 with a small scatter in the abundances, consistent with a globular cluster progenitor as suggested by previous studies. Both streams exhibit mild enhancements in neutron-capture elements, with averages of [EuII/Fe] = 0.47 ± 0.09 for Turranburra and 0.44 ± 0.05 for Willka Yaku, consistent with enrichment from an r-process event. A similar enrichment is observed in other stellar streams, and we further discuss this signature as it relates to the potential enrichment histories of these two streams.",

author = "Webber, \{K. B.\} and Hansen, \{T. T.\} and Marshall, \{J. L.\} and Ji, \{Alexander P.\} and Li, \{Ting S.\} and Costa, \{Gary S. Da\} and Cullinane, \{Lara R.\} and Denis Erkal and Koposov, \{Sergey E.\} and Kyler Kuehn and Lewis, \{Geraint F.\} and Dougal Mackey and Martell, \{Sarah L.\} and Pace, \{Andrew B.\} and Nora Shipp and Simpson, \{Jeffrey D.\} and Zhen Wan and Zucker, \{Daniel B.\} and Alvarado, \{Victor A.\} and Joss Bland-Hawthorn and Guilherme Limberg and Medina, \{Gustavo E.\} and Usman, \{Sam A.\}",

note = "21 pages, 10 tables, 6 figures",

year = "2026",

month = feb,

day = "5",

doi = "10.3847/1538-4357/ae2d59",

language = "English",

volume = "998",

pages = "1--19",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

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Webber, KB, Hansen, TT, Marshall, JL, Ji, AP, Li, TS, Costa, GSD, Cullinane, LR, Erkal, D, Koposov, SE, Kuehn, K, Lewis, GF, Mackey, D, Martell, SL, Pace, AB, Shipp, N, Simpson, JD, Wan, Z, Zucker, DB, Alvarado, VA, Bland-Hawthorn, J, Limberg, G, Medina, GE & Usman, SA 2026, 'Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams', Astrophysical Journal, vol. 998, no. 1, 114, pp. 1-19. https://doi.org/10.3847/1538-4357/ae2d59

TY - JOUR

T1 - Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams

AU - Webber, K. B.

AU - Hansen, T. T.

AU - Marshall, J. L.

AU - Ji, Alexander P.

AU - Li, Ting S.

AU - Costa, Gary S. Da

AU - Cullinane, Lara R.

AU - Erkal, Denis

AU - Koposov, Sergey E.

AU - Kuehn, Kyler

AU - Lewis, Geraint F.

AU - Mackey, Dougal

AU - Martell, Sarah L.

AU - Pace, Andrew B.

AU - Shipp, Nora

AU - Simpson, Jeffrey D.

AU - Wan, Zhen

AU - Zucker, Daniel B.

AU - Alvarado, Victor A.

AU - Bland-Hawthorn, Joss

AU - Limberg, Guilherme

AU - Medina, Gustavo E.

AU - Usman, Sam A.

N1 - 21 pages, 10 tables, 6 figures

PY - 2026/2/5

Y1 - 2026/2/5

N2 - We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/MIKE spectra. Abundances for 27 elements, ranging from carbon to dysprosium, were derived. Our results support the original classification that Turranburra, with a low average metallicity of [Fe/H] = −2.45 ± 0.07, likely originates from a dwarf-galaxy progenitor. Willka Yaku has a low average metallicity of [Fe/H] = −2.35 ± 0.03 with a small scatter in the abundances, consistent with a globular cluster progenitor as suggested by previous studies. Both streams exhibit mild enhancements in neutron-capture elements, with averages of [EuII/Fe] = 0.47 ± 0.09 for Turranburra and 0.44 ± 0.05 for Willka Yaku, consistent with enrichment from an r-process event. A similar enrichment is observed in other stellar streams, and we further discuss this signature as it relates to the potential enrichment histories of these two streams.

AB - We present a detailed chemical abundance analysis of the three brightest known stars from each of the Turranburra and Willka Yaku stellar streams using high-resolution Magellan/MIKE spectra. Abundances for 27 elements, ranging from carbon to dysprosium, were derived. Our results support the original classification that Turranburra, with a low average metallicity of [Fe/H] = −2.45 ± 0.07, likely originates from a dwarf-galaxy progenitor. Willka Yaku has a low average metallicity of [Fe/H] = −2.35 ± 0.03 with a small scatter in the abundances, consistent with a globular cluster progenitor as suggested by previous studies. Both streams exhibit mild enhancements in neutron-capture elements, with averages of [EuII/Fe] = 0.47 ± 0.09 for Turranburra and 0.44 ± 0.05 for Willka Yaku, consistent with enrichment from an r-process event. A similar enrichment is observed in other stellar streams, and we further discuss this signature as it relates to the potential enrichment histories of these two streams.

U2 - 10.3847/1538-4357/ae2d59

DO - 10.3847/1538-4357/ae2d59

M3 - Article

SN - 0004-637X

VL - 998

SP - 1

EP - 19

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 114

ER -

Detailed Chemical Abundance Analysis of the Brightest Stars in the Turranburra and Willka Yaku Stellar Streams

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