Abstract
Stellar ejecta gradually enrich the gas out of which subsequent stars form, making the least chemically enriched stellar systems direct fossils of structures formed in the early Universe1. Although a few hundred stars with metal content below 1,000th of the solar iron content are known in the Galaxy2–4, none of them inhabit globular clusters, some of the oldest known stellar structures. These show metal content of at least approximately 0.2% of the solar metallicity ([Fe / H] ≳ − 2.7). This metallicity floor appears universal5,6, and it has been proposed that protogalaxies that merged into the galaxies we observe today were simply not massive enough to form clusters that survived to the present day7. Here we report observations of a stellar stream, C-19, whose metallicity is less than 0.05% of the solar metallicity ([Fe/H]=−3.38±0.06(statistical)±0.20(systematic)). The low metallicity dispersion and the chemical abundances of the C-19 stars show that this stream is the tidal remnant of the most metal-poor globular cluster ever discovered, and is significantly below the purported metallicity floor: clusters with significantly lower metallicities than observed today existed in the past and contributed their stars to the Milky Way halo.
| Original language | English |
|---|---|
| Pages (from-to) | 45-48 |
| Number of pages | 4 |
| Journal | Nature |
| Volume | 601 |
| Issue number | 7891 |
| DOIs | |
| Publication status | Published - 6-Jan-2022 |
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A stellar stream remnant of a globular cluster below the metallicity floor. / Martin, Nicolas F.; Venn, Kim A.; Aguado, David S. et al.
In: Nature, Vol. 601, No. 7891, 06.01.2022, p. 45-48.Research output: Contribution to journal › Article › Academic › peer-review
TY - JOUR
T1 - A stellar stream remnant of a globular cluster below the metallicity floor
AU - Martin, Nicolas F.
AU - Venn, Kim A.
AU - Aguado, David S.
AU - Starkenburg, Else
AU - González Hernández, Jonay I.
AU - Ibata, Rodrigo A.
AU - Bonifacio, Piercarlo
AU - Caffau, Elisabetta
AU - Sestito, Federico
AU - Arentsen, Anke
AU - Allende Prieto, Carlos
AU - Carlberg, Raymond G.
AU - Fabbro, Sébastien
AU - Fouesneau, Morgan
AU - Hill, Vanessa
AU - Jablonka, Pascale
AU - Kordopatis, Georges
AU - Lardo, Carmela
AU - Malhan, Khyati
AU - Mashonkina, Lyudmila I.
AU - McConnachie, Alan W.
AU - Navarro, Julio F.
AU - Sánchez-Janssen, Rubén
AU - Thomas, Guillaume F.
AU - Yuan, Zhen
AU - Mucciarelli, Alessio
N1 - Funding Information: Acknowledgements N.F.M., R.A.I., A.A. and Z.Y. gratefully acknowledge support from the French National Research Agency (ANR)-funded project Pristine (ANR-18-CE31-0017) along with funding from Centre National de la Recherche Scientifique (CNRS)–INSU through the Programme National de Cosmologie et Galaxies and through CNRS grant PICS07708 and from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 834148). K.A.V. is grateful for funding through the National Science and Engineering Research Council of Canada (NSERC) Discovery Grants and CREATE programmes. E.S. acknowledges funding through VIDI grant ‘Pushing Galactic Archaeology to its Limits’ (project number VI.Vidi.193.093), which is funded by the Dutch Research Council (NWO). J.I.G.H. acknowledges financial support from Spanish Ministry of Science and Innovation (MICINN) project AYA2017-86389-P, and also from the Spanish MICINN under the 2013 Ramón y Cajal programme (RYC-2013-14875). G.F.T. acknowledges support from the Agencia Estatal de Investigación of the Spanish MCINN (grant number FJC2018-037323-I). We thank the Canada–France–Hawaii Telescope (CFHT) staff for performing the Pristine observations in queue mode, for their reactivity in adapting the schedule and for answering questions during the data-reduction process. We are also grateful to the High Performance Computing Centre of the University of Strasbourg and its staff for very generous time allocation and for their support during the development of the STREAMFINDER project. This research used the SIMBAD database70, managed and run at CDS, Strasbourg, France. This research used the VizieR catalogue access tool71, CDS, Strasbourg, France. This work is based on observations obtained with MegaPrime–MegaCam, a joint project of the CFHT and CEA– DAPNIA, at the CFHT, which is operated by the National Research Council of Canada, the Institut National des Science de l’Univers of the French CNRS and the University of Hawaii. ESPaDOnS is a collaborative project funded by France (CNRS, MENESR, OMP, and LATT), Canada (NSERC), the CFHT and the European Space Agency. Data were reduced with use of the CFHT-developed OPERA data-reduction pipeline. We recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the Indigenous Hawaiian community. We are very fortunate to have had the opportunity to conduct observations from this mountain. This work is based on observations obtained with Gemini Remote Access to CFHT ESPaDOnS Spectrograph (GRACES), as part of the Gemini Large and Long Program, GN-2020B-LP-102. The international Gemini Observatory, a program of NSF’s NOIRLab, is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation, on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil) and Korea Astronomy and Space Science Institute (Republic of Korea). This work is based on observations made with the GTC telescope, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, under Director’s Discretionary Time. This work was partly based on data obtained with the instrument OSIRIS, built by a consortium led by the Instituto de Astrofísica de Canarias in collaboration with the Instituto de Astronomía of the Universidad Autónoma de México. OSIRIS was funded by GRANTECAN and the National Plan of Astronomy and Astrophysics of the Spanish Government. This work used data from the European Space Agency 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. Guo Shoujing Telescope (LAMOST) is a national major scientific project of the Chinese Academy of Sciences. Funding for the project was provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. Publisher Copyright: © 2022, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2022/1/6
Y1 - 2022/1/6
N2 - Stellar ejecta gradually enrich the gas out of which subsequent stars form, making the least chemically enriched stellar systems direct fossils of structures formed in the early Universe1. Although a few hundred stars with metal content below 1,000th of the solar iron content are known in the Galaxy2–4, none of them inhabit globular clusters, some of the oldest known stellar structures. These show metal content of at least approximately 0.2% of the solar metallicity ([Fe / H] ≳ − 2.7). This metallicity floor appears universal5,6, and it has been proposed that protogalaxies that merged into the galaxies we observe today were simply not massive enough to form clusters that survived to the present day7. Here we report observations of a stellar stream, C-19, whose metallicity is less than 0.05% of the solar metallicity ([Fe/H]=−3.38±0.06(statistical)±0.20(systematic)). The low metallicity dispersion and the chemical abundances of the C-19 stars show that this stream is the tidal remnant of the most metal-poor globular cluster ever discovered, and is significantly below the purported metallicity floor: clusters with significantly lower metallicities than observed today existed in the past and contributed their stars to the Milky Way halo.
AB - Stellar ejecta gradually enrich the gas out of which subsequent stars form, making the least chemically enriched stellar systems direct fossils of structures formed in the early Universe1. Although a few hundred stars with metal content below 1,000th of the solar iron content are known in the Galaxy2–4, none of them inhabit globular clusters, some of the oldest known stellar structures. These show metal content of at least approximately 0.2% of the solar metallicity ([Fe / H] ≳ − 2.7). This metallicity floor appears universal5,6, and it has been proposed that protogalaxies that merged into the galaxies we observe today were simply not massive enough to form clusters that survived to the present day7. Here we report observations of a stellar stream, C-19, whose metallicity is less than 0.05% of the solar metallicity ([Fe/H]=−3.38±0.06(statistical)±0.20(systematic)). The low metallicity dispersion and the chemical abundances of the C-19 stars show that this stream is the tidal remnant of the most metal-poor globular cluster ever discovered, and is significantly below the purported metallicity floor: clusters with significantly lower metallicities than observed today existed in the past and contributed their stars to the Milky Way halo.
UR - http://www.scopus.com/inward/record.url?scp=85122303378&partnerID=8YFLogxK
U2 - 10.1038/s41586-021-04162-2
DO - 10.1038/s41586-021-04162-2
M3 - Article
C2 - 34987215
AN - SCOPUS:85122303378
SN - 0028-0836
VL - 601
SP - 45
EP - 48
JO - Nature
JF - Nature
IS - 7891
ER -