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  4. The Pristine survey - XV. A CHIT ESPaDOnS view on the Milky Way halo and disc populations
 
research article

The Pristine survey - XV. A CHIT ESPaDOnS view on the Milky Way halo and disc populations

Lucchesi, R.
•
Lardo, C.  
•
Jablonka, P.  
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February 3, 2022
Monthly Notices Of The Royal Astronomical Society

We present a one-dimensional, local thermodynamic equilibrium homogeneous analysis of 132 stars observed at high resolution with ESPaDOnS. This represents the largest sample observed at high resolution (R similar to 40 000) from the Pristine survey. This sample is based on the first version of the Pristine catalogue and covers the full range of metallicities from [Fe/II] similar to-3 to similar to+0.25, with nearly half of our sample (58 stars) composed of very metal-poor (VMP) stars ([Fe/H] <= -2). This wide range of metallicities provides the opportunity of a new detailed study of the Milky Way stellar population. Because it includes both dwarf and giant stars, it also enables the analysis of any potential bias induced by the Pristine selection process. Based on Gaia EDR3, the orbital analysis of this Pristine-ESPaDOnS sample shows that it is composed of 65 halo stars and 67 disc stars. After a general assessment of the sample chemical properties with the alpha-elements Mg and Ca, we focus on the abundance of carbon and the neutron capture elements Ba and Sr. While most of our VMP subsample is carbon normal, we also find that 14 stars out of the 38 stars with [Fe/H] <= -2 and measured carbon abundances turn out to be carbon-enhanced metal-poor (CEMP) stars. We show that these CEMP stars are nearly exclusively (i.e. 12 stars out of 14) in the regime of low luminosity, unevolved, dwarf stars, which we interpret as the consequence of bias of the Pristine filter against C-rich giants. Among the VMP stars, we identify two CEMP stars with no enhancement in neutron-capture process elements and another one enriched in s-process element. Finally, one VMP star is found with a very low [Sr/Fe] abundance ratio for its metallicity, as expected if it had been accreted from an ultra-faint dwarf galaxy.

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Type
research article
DOI
10.1093/mnras/stab3721
Web of Science ID

WOS:000770033600014

Author(s)
Lucchesi, R.
•
Lardo, C.  
•
Jablonka, P.  
•
Sestito, F.
•
Mashonkina, L.
•
Arentsen, A.
•
Suter, W.
•
Venn, K.
•
Martin, N.
•
Starkenburg, E.
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Date Issued

2022-02-03

Publisher

OXFORD UNIV PRESS

Published in
Monthly Notices Of The Royal Astronomical Society
Volume

511

Issue

1

Start page

1004

End page

1021

Subjects

Astronomy & Astrophysics

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stars: abundances

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galaxies: dwarf

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galaxies: formation

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local group

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metal-poor stars

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r-process nucleosynthesis

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low-metallicity stars

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giant branch stars

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digital sky survey

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galactic evolution

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neutron-stars

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discovery

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collapse

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carbon

Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASTRO  
Available on Infoscience
April 11, 2022
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/187081
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