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Origin of metals in old Milky Way halo stars based on GALAH and Gaia

Ishigaki, Miho N. and Hartwig, Tilman and Tarumi, Yuta and Leung, Shing-Chi and Tominaga, Nozomu and Kobayashi, Chiaki and Magg, Mattis and Simionescu, Aurora and Nomoto, Ken’ichi (2021) Origin of metals in old Milky Way halo stars based on GALAH and Gaia. Monthly Notices of the Royal Astronomical Society, 506 (4). pp. 5410-5429. ISSN 0035-8711. doi:10.1093/mnras/stab1982.

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Stellar and supernova nucleosynthesis in the first few billion years of the cosmic history have set the scene for early structure formation in the Universe, while little is known about their nature. Making use of stellar physical parameters measured by GALAH Data Release 3 with accurate astrometry from the Gaia EDR3, we have selected ∼100 old main-sequence turn-off stars (ages ≳12 Gyr) with kinematics compatible with the Milky Way stellar halo population in the Solar neighbourhood. Detailed homogeneous elemental abundance estimates by GALAH DR3 are compared with supernova yield models of Pop III (zero-metal) core-collapse supernovae (CCSNe), normal (non-zero-metal) CCSNe, and Type Ia supernovae (SN Ia) to examine which of the individual yields or their combinations best reproduce the observed elemental abundance patterns for each of the old halo stars (‘OHS’). We find that the observed abundances in the OHS with [Fe/H] > −1.5 are best explained by contributions from both CCSNe and SN Ia, where the fraction of SN Ia among all the metal-enriching SNe is up to 10–20 per cent for stars with high [Mg/Fe] ratios and up to 20–27 per cent for stars with low [Mg/Fe] ratios, depending on the assumption about the relative fraction of near-Chandrasekhar-mass SNe Ia progenitors. The results suggest that, in the progenitor systems of the OHS with [Fe/H] > −1.5, ∼ 50–60 per cent of Fe mass originated from normal CCSNe at the earliest phases of the Milky Way formation. These results provide an insight into the birth environments of the oldest stars in the Galactic halo.

Item Type:Article
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URLURL TypeDescription Paper
Ishigaki, Miho N.0000-0003-4656-0241
Hartwig, Tilman0000-0001-6742-8843
Tarumi, Yuta0000-0002-9801-7788
Leung, Shing-Chi0000-0002-4972-3803
Tominaga, Nozomu0000-0001-8537-3153
Kobayashi, Chiaki0000-0002-4343-0487
Magg, Mattis0000-0002-9022-5136
Simionescu, Aurora0000-0002-9714-3862
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 July 7. Received 2021 July 7; in original form 2020 September 17. Published: 13 July 2021. The authors thank the anonymous referee for useful comments, which significantly improved this manuscript. We are very grateful to S. Sharma for helpful assistance on stellar ages from GALAH DR3. This work has been supported by the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. This work has also been supported by JSPS KAKENHI Grant Numbers 17K14249, 18H05437, 20H05855 (MNI), 19K23437, 20K14464 (TH), JP17K05382 and JP20K04024 (KN), JP21H04499 (MNI, NT, and KN). SCL acknowledges support by NASA grants HST-AR-15021.001-A and 80NSSC18K101. AS is supported by the Women In Science Excel (WISE) programme of the Netherlands Organisation for Scientific Research (NWO), and acknowledges the World Premier Research Center Initiative (WPI) and the Kavli IPMU for the continued hospitality. SRON Netherlands Institute for Space Research is supported financially by NWO. CK acknowledges funding from the UK Science and Technology Facility Council (STFC) through grant ST/M000958/1 and ST/R000905/1. This work was supported in part by the National Science Foundation under Grant No. OISE-1927130 (IReNA). This work made use of the Third Data Release of the GALAH Survey (Buder et al. 2021). The GALAH Survey is based on data acquired through the Australian Astronomical Observatory, under programs: A/2013B/13 (The GALAH pilot survey); A/2014A/25, A/2015A/19, A2017A/18 (The GALAH survey phase 1); A2018A/18 (Open clusters with HERMES); A2019A/1 (Hierarchical star formation in Ori OB1); A2019A/15 (The GALAH survey phase 2); A/2015B/19, A/2016A/22, A/2016B/10, A/2017B/16, A/2018B/15 (The HERMES-TESS program); and A/2015A/3, A/2015B/1, A/2015B/19, A/2016A/22, A/2016B/12, A/2017A/14 (The HERMES K2-follow-up program). We acknowledge the traditional owners of the land on which the AAT stands, the Gamilaraay people, and pay our respects to elders past and present. This paper includes data that has been provided by AAO Data Central ( This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research made use of Astropy,4 a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013; Price-Whelan et al. 2018), GALPY (Bovy 2015), NUMPY (Van Der Walt, Colbert & Varoquaux 2011), Matplotlib (Hunter 2007), SCIPY (Virtanen et al. 2020), PANDAS (McKinney 2010, 2011), and PYMC3 (Salvatier 2016). Data Availability: The data underlying this article will be shared on request to the corresponding author.
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)17K14249
Japan Society for the Promotion of Science (JSPS)18H05437
Japan Society for the Promotion of Science (JSPS)20H05855
Japan Society for the Promotion of Science (JSPS)19K23437
Japan Society for the Promotion of Science (JSPS)20K14464
Japan Society for the Promotion of Science (JSPS)JP17K05382
Japan Society for the Promotion of Science (JSPS)JP20K04024
Japan Society for the Promotion of Science (JSPS)JP21H04499
NASA Hubble FellowshipHST-AR-15021.001-A
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/M000958/1
Science and Technology Facilities Council (STFC)ST/R000905/1
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:nuclear reactions, nucleosynthesis, abundances – stars: abundances – stars: fundamental parameters – stars: kinematics and dynamics – stars: Population III – supernovae: general
Issue or Number:4
Record Number:CaltechAUTHORS:20211110-215821371
Persistent URL:
Official Citation:Miho N Ishigaki, Tilman Hartwig, Yuta Tarumi, Shing-Chi Leung, Nozomu Tominaga, Chiaki Kobayashi, Mattis Magg, Aurora Simionescu, Ken’ichi Nomoto, Origin of metals in old Milky Way halo stars based on GALAH and Gaia, Monthly Notices of the Royal Astronomical Society, Volume 506, Issue 4, October 2021, Pages 5410–5429,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111833
Deposited By: Tony Diaz
Deposited On:11 Nov 2021 18:13
Last Modified:11 Nov 2021 18:13

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