Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*

Andrew R. Casey; Alexander P. Ji; Terese T. Hansen; Ting S. Li; Sergey E Koposov; Gary S. Da Costa; Joss Bland-Hawthorn; Lara Cullinane; Denis Erkal; Geraint F Lewis; Kyler Kuehn; Dougal Mackey; Sarah L. Martell; Andrew B. Pace; Jeffrey D. Simpson; Daniel B. Zucker

doi:10.3847/1538-4357/ac1346

Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*

Andrew R. Casey^*, Alexander P. Ji, Terese T. Hansen, Ting S. Li, Sergey E Koposov, Gary S. Da Costa, Joss Bland-Hawthorn, Lara Cullinane, Denis Erkal, Geraint F Lewis, Kyler Kuehn, Dougal Mackey, Sarah L. Martell, Andrew B. Pace, Jeffrey D. Simpson, Daniel B. Zucker

^*Corresponding author for this work

School of Physics and Astronomy

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

Abstract

The Phoenix stellar stream has a low intrinsic dispersion in velocity and metallicity that implies the progenitor was probably a low mass globular cluster. In this work we use Magellan/MIKE highdispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity (σ([Fe II/H]) = 0.04+0:11-0:03) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters. However, unlike any other globular cluster, we also find an intrinsic spread in [Sr II/Fe] spanning ~1 dex, while [Ba II/Fe] shows nearly no intrinsic spread
(σ([Ba II/H]) = 0.03+0.10-0.02). This abundance signature is best interpreted as slow neutron capture element production from a massive fast-rotating metal-poor star (15-20M, vini/vcrit = 0.4, [Fe/H] =-3.8). The low inferred cluster mass suggests the system would have been unable to retain supernovae ejecta, implying that any massive fast-rotating metal-poor star that enriched the interstellar medium must have formed and evolved before the globular cluster formed. Neutron capture element production from asymptotic giant branch stars or magneto-rotational instabilities in core-collapse supernovae provide poor fits to the observations. We also report one Phoenix stream star to be a lithium-rich
giant (A(Li) = 3.1 ± 0.1). At [Fe/H] = -2:93 it is among the most metal-poor lithium-rich giants known.

Original language	English
Article number	67
Pages (from-to)	1-14
Number of pages	14
Journal	Astrophysical Journal
Volume	921
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ac1346
Publication status	Published - 1 Nov 2021

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Casey, A. R., Ji, A. P., Hansen, T. T., Li, T. S., Koposov, S. E., Costa, G. S. D., Bland-Hawthorn, J., Cullinane, L., Erkal, D., Lewis, G. F., Kuehn, K., Mackey, D., Martell, S. L., Pace, A. B., Simpson, J. D., & Zucker, D. B. (2021). Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*. Astrophysical Journal, 921(1), 1-14. Article 67. https://doi.org/10.3847/1538-4357/ac1346

@article{fd48b3668bc840a8a36493f6387c23a9,

title = "Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*",

abstract = "The Phoenix stellar stream has a low intrinsic dispersion in velocity and metallicity that implies the progenitor was probably a low mass globular cluster. In this work we use Magellan/MIKE highdispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity (σ([Fe II/H]) = 0.04+0:11-0:03) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters. However, unlike any other globular cluster, we also find an intrinsic spread in [Sr II/Fe] spanning ~1 dex, while [Ba II/Fe] shows nearly no intrinsic spread(σ([Ba II/H]) = 0.03+0.10-0.02). This abundance signature is best interpreted as slow neutron capture element production from a massive fast-rotating metal-poor star (15-20M, vini/vcrit = 0.4, [Fe/H] =-3.8). The low inferred cluster mass suggests the system would have been unable to retain supernovae ejecta, implying that any massive fast-rotating metal-poor star that enriched the interstellar medium must have formed and evolved before the globular cluster formed. Neutron capture element production from asymptotic giant branch stars or magneto-rotational instabilities in core-collapse supernovae provide poor fits to the observations. We also report one Phoenix stream star to be a lithium-richgiant (A(Li) = 3.1 ± 0.1). At [Fe/H] = -2:93 it is among the most metal-poor lithium-rich giants known.",

author = "Casey, {Andrew R.} and Ji, {Alexander P.} and Hansen, {Terese T.} and Li, {Ting S.} and Koposov, {Sergey E} and Costa, {Gary S. Da} and Joss Bland-Hawthorn and Lara Cullinane and Denis Erkal and Lewis, {Geraint F} and Kyler Kuehn and Dougal Mackey and Martell, {Sarah L.} and Pace, {Andrew B.} and Simpson, {Jeffrey D.} and Zucker, {Daniel B.}",

year = "2021",

month = nov,

day = "1",

doi = "10.3847/1538-4357/ac1346",

language = "English",

volume = "921",

pages = "1--14",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing",

number = "1",

}

Casey, AR, Ji, AP, Hansen, TT, Li, TS, Koposov, SE, Costa, GSD, Bland-Hawthorn, J, Cullinane, L, Erkal, D, Lewis, GF, Kuehn, K, Mackey, D, Martell, SL, Pace, AB, Simpson, JD & Zucker, DB 2021, 'Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*', Astrophysical Journal, vol. 921, no. 1, 67, pp. 1-14. https://doi.org/10.3847/1538-4357/ac1346

TY - JOUR

T1 - Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*

AU - Casey, Andrew R.

AU - Ji, Alexander P.

AU - Hansen, Terese T.

AU - Li, Ting S.

AU - Koposov, Sergey E

AU - Costa, Gary S. Da

AU - Bland-Hawthorn, Joss

AU - Cullinane, Lara

AU - Erkal, Denis

AU - Lewis, Geraint F

AU - Kuehn, Kyler

AU - Mackey, Dougal

AU - Martell, Sarah L.

AU - Pace, Andrew B.

AU - Simpson, Jeffrey D.

AU - Zucker, Daniel B.

PY - 2021/11/1

Y1 - 2021/11/1

N2 - The Phoenix stellar stream has a low intrinsic dispersion in velocity and metallicity that implies the progenitor was probably a low mass globular cluster. In this work we use Magellan/MIKE highdispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity (σ([Fe II/H]) = 0.04+0:11-0:03) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters. However, unlike any other globular cluster, we also find an intrinsic spread in [Sr II/Fe] spanning ~1 dex, while [Ba II/Fe] shows nearly no intrinsic spread(σ([Ba II/H]) = 0.03+0.10-0.02). This abundance signature is best interpreted as slow neutron capture element production from a massive fast-rotating metal-poor star (15-20M, vini/vcrit = 0.4, [Fe/H] =-3.8). The low inferred cluster mass suggests the system would have been unable to retain supernovae ejecta, implying that any massive fast-rotating metal-poor star that enriched the interstellar medium must have formed and evolved before the globular cluster formed. Neutron capture element production from asymptotic giant branch stars or magneto-rotational instabilities in core-collapse supernovae provide poor fits to the observations. We also report one Phoenix stream star to be a lithium-richgiant (A(Li) = 3.1 ± 0.1). At [Fe/H] = -2:93 it is among the most metal-poor lithium-rich giants known.

AB - The Phoenix stellar stream has a low intrinsic dispersion in velocity and metallicity that implies the progenitor was probably a low mass globular cluster. In this work we use Magellan/MIKE highdispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity (σ([Fe II/H]) = 0.04+0:11-0:03) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters. However, unlike any other globular cluster, we also find an intrinsic spread in [Sr II/Fe] spanning ~1 dex, while [Ba II/Fe] shows nearly no intrinsic spread(σ([Ba II/H]) = 0.03+0.10-0.02). This abundance signature is best interpreted as slow neutron capture element production from a massive fast-rotating metal-poor star (15-20M, vini/vcrit = 0.4, [Fe/H] =-3.8). The low inferred cluster mass suggests the system would have been unable to retain supernovae ejecta, implying that any massive fast-rotating metal-poor star that enriched the interstellar medium must have formed and evolved before the globular cluster formed. Neutron capture element production from asymptotic giant branch stars or magneto-rotational instabilities in core-collapse supernovae provide poor fits to the observations. We also report one Phoenix stream star to be a lithium-richgiant (A(Li) = 3.1 ± 0.1). At [Fe/H] = -2:93 it is among the most metal-poor lithium-rich giants known.

U2 - 10.3847/1538-4357/ac1346

DO - 10.3847/1538-4357/ac1346

M3 - Article

SN - 0004-637X

VL - 921

SP - 1

EP - 14

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 67

ER -

Signature of a massive rotating metal-poor star imprinted in the Phoenix stellar stream*

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