1. The Pristine Inner Galaxy Survey (PIGS) II: Uncovering the most metal-poor populations in the inner Milky Way
- Author
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Geraint F. Lewis, Jeffrey D. Simpson, Nicolas F. Martin, Zhen Wan, David Aguado, Kim A. Venn, Daniel B. Zucker, Anke Arentsen, Carlos Allende Prieto, Lyudmila Mashonkina, Rubén Sánchez-Janssen, Jonay I. González Hernández, Else Starkenburg, J. E. O'Connell, Julio F. Navarro, K. Youakim, Roger E. Cohen, Guillaume F. Thomas, Doug Geisler, Raymond G. Carlberg, Mathias Schultheis, Vanessa Hill, Leibniz Institute for Astrophysics Potsdam (AIP), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Astronomy, University of Cambridge, Universidad de La Laguna [Tenerife - SP] (ULL), Joseph Louis LAGRANGE (LAGRANGE), Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA), University of British Columbia (UBC), Department of Astronomy and Astrophysics [Universty of Toronto], University of Toronto, Leibniz-Institut für Astrophysik Potsdam (AIP), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Macquarie University, Instituto de Astrofisica de Canarias (IAC), Departamento de Astrofísica [La laguna], Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Victoria], University of Victoria [Canada] (UVIC), Institute of Astronomy of the Russian Academy of Sciences (INASAN), Russian Academy of Sciences [Moscow] (RAS), UK Astronomy Technology Centre (UK ATC), Science and Technology Facilities Council (STFC), NRC Herzberg Astronomy and Astrophysics, Conseil National de Recherches Canada (CNRC), Sydney Institute for Astronomy (SIfA), The University of Sydney, School of Physics [UNSW Sydney] (UNSW), University of New South Wales [Sydney] (UNSW), Space Telescope Science Institute (STSci), Departamento de Astronomía [Concepción], Universidad de Concepción - University of Concepcion [Chile], Instituto de Investigación Multidisciplinario en Ciencia y Tecnología, Universidad de La Serena (USERENA), Departamento de Física y Astronomía [La Serena], Astronomy, and Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France.
- Subjects
Metallicity ,Milky Way ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,Galaxy: bulge ,Photometry (optics) ,techniques: photometric ,Bulge ,0103 physical sciences ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,ComputingMilieux_MISCELLANEOUS ,Physics ,Galaxy: stellar content ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,010308 nuclear & particles physics ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Cosmic distance ladder ,Astronomy and Astrophysics ,stars: Population II ,Horizontal branch ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,[SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA] ,stars: fundamental parameters ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,techniques: spectroscopic - Abstract
Metal-poor stars are important tools for tracing the early history of the Milky Way, and for learning about the first generations of stars. Simulations suggest that the oldest metal-poor stars are to be found in the inner Galaxy. Typical bulge surveys, however, lack low metallicity ([Fe/H] < -1.0) stars because the inner Galaxy is predominantly metal-rich. The aim of the Pristine Inner Galaxy Survey (PIGS) is to study the metal-poor and very metal-poor (VMP, [Fe/H] < -2.0) stars in this region. In PIGS, metal-poor targets for spectroscopic follow-up are selected from metallicity-sensitive CaHK photometry from the CFHT. This work presents the ~250 deg^2 photometric survey as well as intermediate-resolution spectroscopic follow-up observations for ~8000 stars using AAOmega on the AAT. The spectra are analysed using two independent tools: ULySS with an empirical spectral library, and FERRE with a library of synthetic spectra. The comparison between the two methods enables a robust determination of the stellar parameters and their uncertainties. We present a sample of 1300 VMP stars -- the largest sample of VMP stars in the inner Galaxy to date. Additionally, our spectroscopic dataset includes ~1700 horizontal branch stars, which are useful metal-poor standard candles. We furthermore show that PIGS photometry selects VMP stars with unprecedented efficiency: 86%/80% (lower/higher extinction) of the best candidates satisfy [Fe/H] < -2.0, as do 80%/63% of a larger, less strictly selected sample. We discuss future applications of this unique dataset that will further our understanding of the chemical and dynamical evolution of the innermost regions of our Galaxy., accepted for publication in MNRAS, 17 pages, 9 figures
- Published
- 2020
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