Статья

The Pristine survey IV: approaching the Galactic metallicity floor with the discovery of an ultra-metal-poor star

Else StarkenburgLeibniz Institute for Astrophyics Potsdam (AIP), Ander Sternwarte 16, D-14482 Potsdam, GermanyDavid S. AguadoDepartamento de Astrofsica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, SpainP. BonifacioGEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen, F-92190 Meudon, FranceE. CaffauGEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen, F-92190 Meudon, FranceP. JablonkaGEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen, F-92190 Meudon, FranceC. LardoInstitute of Physics, Laboratoire d’astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire, CH-1290 Versoix, SwitzerlandNicolas F. MartinMax-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, GermanyRubén Sánchez-JanssenUK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UKFederico SestitoObservatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, FranceKim A. VennDepartment of Physics and Astronomy, University of Victoria, PO Box 3055, STN CSC, Victoria BC V8W 3P6, CanadaKris YouakimLeibniz Institute for Astrophyics Potsdam (AIP), Ander Sternwarte 16, D-14482 Potsdam, GermanyCarlos Allende PrietoDepartamento de Astrofsica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, SpainAnke ArentsenLeibniz Institute for Astrophyics Potsdam (AIP), Ander Sternwarte 16, D-14482 Potsdam, GermanyMarc GentileInstitute of Physics, Laboratoire d’astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire, CH-1290 Versoix, SwitzerlandJ. I. Gónzalez HernándezDepartamento de Astrofsica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, SpainCollin KieltyDepartment of Physics and Astronomy, University of Victoria, PO Box 3055, STN CSC, Victoria BC V8W 3P6, CanadaHelmer H. KoppelmanKapteyn Astronomical Institute, University of Groningen, Landleven 12, NL-9747AD Groningen, the NetherlandsNicolas LongeardObservatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, FranceEline TolstoyKapteyn Astronomical Institute, University of Groningen, Landleven 12, NL-9747AD Groningen, the NetherlandsR. G. CarlbergDepartment of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4, CanadaPatrick CôtéNRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, CanadaM. FouesneauMax-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, GermanyV. HillLaboratoire Lagrange, Université de Nice Sophia-Antipolis, Observatoire de la Côte d’Azur, CNRS, Bd de l’Observatoire, CS 34229, F-06304 Nice cedex 4, FranceAlan W. McConnachieNRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, CanadaJulio F. NavarroDepartment of Physics and Astronomy, University of Victoria, PO Box 3055, STN CSC, Victoria BC V8W 3P6, Canada

2018en

ABI

Аннотация

The early Universe presented a star formation environment that was almost devoid of heavy elements. The lowest metallicity stars thus provide a unique window into the earliest Galactic stages, but are exceedingly rare and difficult to find. Here, we present the discovery of an ultra-metal-poor star, Pristine_221.8781+9.7844, using narrow-band Ca H&amp;K photometry from the Pristine survey. Follow-up medium- and high-resolution spectroscopy confirms the ultra-metal-poor nature of Pristine_221.8781+9.7844 ([Fe/H] = -4.66 ± 0.13 in 1D LTE) with an enhancement of 0.3-0.4 dex in α-elements relative to Fe, and an unusually low carbon abundance. We derive an upper limit of A(C) = 5.6, well below typical A(C) values for such ultra-metal-poor stars. This makes Pristine_221.8781+9.7844 one of the most metal-poor stars; in fact, it is very similar to the most metal-poor star known (SDSS J102915+172927). The existence of a class of ultra-metal-poor stars with low(er) carbon abundances suggest that there must have been several formation channels in the early Universe through which long-lived, low- mass stars were formed.

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Идентификаторы

DOI: 10.1093/mnras/sty2276

Цитирования и источники

Цитирований: 2Использованных источников: 0

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