The GALAH survey: Accreted stars also inhabit the Spite plateau

the GALAH collaboration

doi:10.1093/mnras/stab2012

The GALAH survey: Accreted stars also inhabit the Spite plateau

the GALAH collaboration

School of Physics and Astronomy

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

11 Citations (Scopus)

Abstract

The European Space Agency (ESA) Gaia mission has enabled the remarkable discovery that a large fraction of the stars near the solar neighbourhood are debris from a single in-falling system, the so-called Gaia-Sausage-Enceladus (GSE). This discovery provides astronomers for the first time with a large cohort of easily observable, unevolved stars that formed in a single extragalactic environment. Here we use these stars to investigate the 'Spite plateau' - the near-constant lithium abundance observed in unevolved metal-poor stars across a wide range of metallicities (-3 < [Fe/H] < -1). Our aim is to test whether individual galaxies could have different Spite plateaus - e.g. the interstellar medium could be more depleted in lithium in a lower galactic mass system due to it having a smaller reservoir of gas. We identified 93 GSE dwarf stars observed and analysed by the GALactic Archaeology with HERMES (GALAH) survey as part of its Data Release 3 (DR3). Orbital actions were used to select samples of GSE stars, and comparison samples of halo and disc stars. We find that the GSE stars show the same lithium abundance as other likely accreted stars and in situ Milky Way stars. Formation environment leaves no imprint on lithium abundances. This result fits within the growing consensus that the Spite plateau, and more generally the 'cosmological lithium problem' - the observed discrepancy between the amount of lithium in warm, metal-poor dwarf stars in our Galaxy, and the amount of lithium predicted to have been produced by big bang nucleosynthesis - is the result of lithium depletion processes within stars.

Original language	English
Pages (from-to)	43-54
Number of pages	12
Journal	Monthly Notices of the Royal Astronomical Society
Volume	507
Issue number	1
DOIs	https://doi.org/10.1093/mnras/stab2012
Publication status	Published - Oct 2021

Keywords

Galaxy: evolution
Galaxy: halo
stars: abundances

Access to Document

10.1093/mnras/stab2012

Cite this

@article{b8f33d6686ca4895a64941030515f625,

title = "The GALAH survey: Accreted stars also inhabit the Spite plateau",

abstract = "The European Space Agency (ESA) Gaia mission has enabled the remarkable discovery that a large fraction of the stars near the solar neighbourhood are debris from a single in-falling system, the so-called Gaia-Sausage-Enceladus (GSE). This discovery provides astronomers for the first time with a large cohort of easily observable, unevolved stars that formed in a single extragalactic environment. Here we use these stars to investigate the 'Spite plateau' - the near-constant lithium abundance observed in unevolved metal-poor stars across a wide range of metallicities (-3 < [Fe/H] < -1). Our aim is to test whether individual galaxies could have different Spite plateaus - e.g. the interstellar medium could be more depleted in lithium in a lower galactic mass system due to it having a smaller reservoir of gas. We identified 93 GSE dwarf stars observed and analysed by the GALactic Archaeology with HERMES (GALAH) survey as part of its Data Release 3 (DR3). Orbital actions were used to select samples of GSE stars, and comparison samples of halo and disc stars. We find that the GSE stars show the same lithium abundance as other likely accreted stars and in situ Milky Way stars. Formation environment leaves no imprint on lithium abundances. This result fits within the growing consensus that the Spite plateau, and more generally the 'cosmological lithium problem' - the observed discrepancy between the amount of lithium in warm, metal-poor dwarf stars in our Galaxy, and the amount of lithium predicted to have been produced by big bang nucleosynthesis - is the result of lithium depletion processes within stars. ",

keywords = "Galaxy: evolution, Galaxy: halo, stars: abundances",

author = "Simpson, {Jeffrey D.} and Martell, {Sarah L.} and Sven Buder and Joss Bland-Hawthorn and Casey, {Andrew R.} and {De Silva}, {Gayandhi M.} and Valentina D'Orazi and Freeman, {Ken C.} and Michael Hayden and Janez Kos and Lewis, {Geraint F.} and Karin Lind and Schlesinger, {Katharine J.} and Sanjib Sharma and Dennis Stello and Zucker, {Daniel B.} and Toma{\v z} Zwitter and Martin Asplund and {Da Costa}, Gary and Klemen {\v C}otar and Thor Tepper-Garc{\'i}a and Jonathan Horner and Thomas Nordlander and Ting, {Yuan Sen} and Wyse, {Rosemary F.G.} and {the GALAH collaboration}",

note = "Funding Information: The GALAH survey is based on observations made at the Anglo-Australian Telescope, under programmes A/2013B/13, A/2014A/25, A/2015A/19, and A/2017A/18. We acknowledge the traditional owners of the land on which the AAT stands, the Gamilaraay people, and pay our respects to elders past, present, and emerging. This paper includes data that have been provided by AAO Data Central (datacentral.org.au). The following software and programming languages made this research possible: PYTHON (v3.9.1); ASTROPY (v4.2; Astropy Collaboration et al. 2018), a community-developed core PYTHON package for astronomy; MATPLOTLIB (v3.3.3; Hunter 2007; Caswell et al. 2020); SCIPY (v1.6.0; Virtanen et al. 2020); and H5PY (v3.1.0). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https: //www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. JDS, SLM, and DBZ acknowledge the support of the Australian Research Council through Discovery Project grant DP180101791. SLM and JDS are supported by the UNSW Scientia Fellowship program. KL acknowledges funds from the European Research Council (ERC) under the European Union's Horizon 2020 Framework Programme (grant agreement no. 852977). Y-ST is grateful to be supported by the NASA Hubble Fellowship grant HST-HF2-51425.001 awarded by the Space Telescope Science Institute. ARC is supported in part by the Australian Research Council through a Discovery Early Career Researcher Award (DE190100656). Publisher Copyright: {\textcopyright} 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.",

year = "2021",

month = oct,

doi = "10.1093/mnras/stab2012",

language = "English",

volume = "507",

pages = "43--54",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "1",

}

TY - JOUR

T1 - The GALAH survey

T2 - Accreted stars also inhabit the Spite plateau

AU - Simpson, Jeffrey D.

AU - Martell, Sarah L.

AU - Buder, Sven

AU - Bland-Hawthorn, Joss

AU - Casey, Andrew R.

AU - De Silva, Gayandhi M.

AU - D'Orazi, Valentina

AU - Freeman, Ken C.

AU - Hayden, Michael

AU - Kos, Janez

AU - Lewis, Geraint F.

AU - Lind, Karin

AU - Schlesinger, Katharine J.

AU - Sharma, Sanjib

AU - Stello, Dennis

AU - Zucker, Daniel B.

AU - Zwitter, Tomaž

AU - Asplund, Martin

AU - Da Costa, Gary

AU - Čotar, Klemen

AU - Tepper-García, Thor

AU - Horner, Jonathan

AU - Nordlander, Thomas

AU - Ting, Yuan Sen

AU - Wyse, Rosemary F.G.

AU - the GALAH collaboration

N1 - Funding Information: The GALAH survey is based on observations made at the Anglo-Australian Telescope, under programmes A/2013B/13, A/2014A/25, A/2015A/19, and A/2017A/18. We acknowledge the traditional owners of the land on which the AAT stands, the Gamilaraay people, and pay our respects to elders past, present, and emerging. This paper includes data that have been provided by AAO Data Central (datacentral.org.au). The following software and programming languages made this research possible: PYTHON (v3.9.1); ASTROPY (v4.2; Astropy Collaboration et al. 2018), a community-developed core PYTHON package for astronomy; MATPLOTLIB (v3.3.3; Hunter 2007; Caswell et al. 2020); SCIPY (v1.6.0; Virtanen et al. 2020); and H5PY (v3.1.0). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https: //www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. JDS, SLM, and DBZ acknowledge the support of the Australian Research Council through Discovery Project grant DP180101791. SLM and JDS are supported by the UNSW Scientia Fellowship program. KL acknowledges funds from the European Research Council (ERC) under the European Union's Horizon 2020 Framework Programme (grant agreement no. 852977). Y-ST is grateful to be supported by the NASA Hubble Fellowship grant HST-HF2-51425.001 awarded by the Space Telescope Science Institute. ARC is supported in part by the Australian Research Council through a Discovery Early Career Researcher Award (DE190100656). Publisher Copyright: © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

PY - 2021/10

Y1 - 2021/10

N2 - The European Space Agency (ESA) Gaia mission has enabled the remarkable discovery that a large fraction of the stars near the solar neighbourhood are debris from a single in-falling system, the so-called Gaia-Sausage-Enceladus (GSE). This discovery provides astronomers for the first time with a large cohort of easily observable, unevolved stars that formed in a single extragalactic environment. Here we use these stars to investigate the 'Spite plateau' - the near-constant lithium abundance observed in unevolved metal-poor stars across a wide range of metallicities (-3 < [Fe/H] < -1). Our aim is to test whether individual galaxies could have different Spite plateaus - e.g. the interstellar medium could be more depleted in lithium in a lower galactic mass system due to it having a smaller reservoir of gas. We identified 93 GSE dwarf stars observed and analysed by the GALactic Archaeology with HERMES (GALAH) survey as part of its Data Release 3 (DR3). Orbital actions were used to select samples of GSE stars, and comparison samples of halo and disc stars. We find that the GSE stars show the same lithium abundance as other likely accreted stars and in situ Milky Way stars. Formation environment leaves no imprint on lithium abundances. This result fits within the growing consensus that the Spite plateau, and more generally the 'cosmological lithium problem' - the observed discrepancy between the amount of lithium in warm, metal-poor dwarf stars in our Galaxy, and the amount of lithium predicted to have been produced by big bang nucleosynthesis - is the result of lithium depletion processes within stars.

AB - The European Space Agency (ESA) Gaia mission has enabled the remarkable discovery that a large fraction of the stars near the solar neighbourhood are debris from a single in-falling system, the so-called Gaia-Sausage-Enceladus (GSE). This discovery provides astronomers for the first time with a large cohort of easily observable, unevolved stars that formed in a single extragalactic environment. Here we use these stars to investigate the 'Spite plateau' - the near-constant lithium abundance observed in unevolved metal-poor stars across a wide range of metallicities (-3 < [Fe/H] < -1). Our aim is to test whether individual galaxies could have different Spite plateaus - e.g. the interstellar medium could be more depleted in lithium in a lower galactic mass system due to it having a smaller reservoir of gas. We identified 93 GSE dwarf stars observed and analysed by the GALactic Archaeology with HERMES (GALAH) survey as part of its Data Release 3 (DR3). Orbital actions were used to select samples of GSE stars, and comparison samples of halo and disc stars. We find that the GSE stars show the same lithium abundance as other likely accreted stars and in situ Milky Way stars. Formation environment leaves no imprint on lithium abundances. This result fits within the growing consensus that the Spite plateau, and more generally the 'cosmological lithium problem' - the observed discrepancy between the amount of lithium in warm, metal-poor dwarf stars in our Galaxy, and the amount of lithium predicted to have been produced by big bang nucleosynthesis - is the result of lithium depletion processes within stars.

KW - Galaxy: evolution

KW - Galaxy: halo

KW - stars: abundances

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U2 - 10.1093/mnras/stab2012

DO - 10.1093/mnras/stab2012

M3 - Article

AN - SCOPUS:85115203707

SN - 0035-8711

VL - 507

SP - 43

EP - 54

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

The GALAH survey: Accreted stars also inhabit the Spite plateau

Abstract

Keywords

Access to Document

Other files and links

The stars that should not exist

ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions

Cite this

The GALAH survey: Accreted stars also inhabit the Spite plateau

Abstract

Keywords

Access to Document

Other files and links

Projects

The stars that should not exist

ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions

Cite this