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  4. The Pristine survey - XX. GTC follow-up observations of extremely metal-poor stars identified from Pristine and LAMOST
 
research article

The Pristine survey - XX. GTC follow-up observations of extremely metal-poor stars identified from Pristine and LAMOST

Arentsen, Anke
•
Aguado, David S.
•
Sestito, Federico
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January 17, 2023
Monthly Notices Of The Royal Astronomical Society

A B S T R A C T Ultra-metal-poor stars ( [Fe / H] < -4 . 0) are very rare, and finding them is a challenging task. Both narrow-band photometry and low-resolution spectroscopy have been useful tools for identifying candidates, and in this work, we combine both approaches. We cross-matched metallicity-sensitive photometry from the Pristine surv e y with the low-resolution spectroscopic Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data base, and re-analysed all LAMOST spectra with [Fe / H]Pristine < -2 . 5. We find that similar to 1/3rd of this sample (selected without [Fe / H]Pristine quality cuts) also have spectroscopic [Fe / H] < -2 . 5. From this sample, containing many low signal-to-noise ratio (S/N) spectra, we selected 11 stars potentially having [Fe / H] < -4 . 0 or [Fe / H] < -3 . 0 with very high carbon abundances, and we performed higher S/N medium-resolution spectroscopic follow-up with the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) on the 10.4-m Gran Telescopio Canarias (GTC). We confirm their extremely low metallicities, with a mean of [Fe / H] = -3 . 4, and the most metal-poor star having [Fe / H] = -3 . 8. Three of these are clearly carbon-enhanced metal-poor (CEMP) stars with + 1 . 65 < [C / Fe] < + 2 . 45. The two most carbon-rich stars are either among the most metal-poor CEMP-s stars or the most carbon-rich CEMP-no stars known, the third is likely a CEMP-no star. We derived orbital properties for the OSIRIS sample and find that only one of our targets can be confidently associated with known substructures/accretion events, and that three out of four inner halo stars have prograde orbits. Large spectroscopic surveys may contain many hidden extremely and ultra-metal-poor stars, and adding additional information from e.g. photometry as in this work can unco v er them more efficiently and confidently.

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Type
research article
DOI
10.1093/mnras/stad043
Web of Science ID

WOS:000919578800009

Author(s)
Arentsen, Anke
Aguado, David S.
Sestito, Federico
Hernandez, Jonay I. Gonzalez
Martin, Nicolas F.
Starkenburg, Else
Jablonka, Pascale  
Yuan, Zhen
Date Issued

2023-01-17

Publisher

OXFORD UNIV PRESS

Published in
Monthly Notices Of The Royal Astronomical Society
Volume

519

Issue

4

Start page

5554

End page

5566

Subjects

Astronomy & Astrophysics

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techniques: spectroscopic

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stars: chemically peculiar

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stars: population ii

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galaxy: halo

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low-metallicity stars

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galaxy survey pigs

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milky-way

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stellar streams

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ancient

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search

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carbon

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abundances

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evolution

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espadons

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASTRO  
Available on Infoscience
March 13, 2023
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/195898
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