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  4. The Pristine survey - V. A bright star sample observed with SOPHIE
 
research article

The Pristine survey - V. A bright star sample observed with SOPHIE

Bonifacio, P.
•
Caffau, E.
•
Sestito, F.
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August 1, 2019
Monthly Notices Of The Royal Astronomical Society

With the aim of probing the properties of the bright end of the Pristine survey and its effectiveness in selecting metal-poor stars, we selected a sample of bright candidate metal-poor stars combining Pristine CaHK photometry with APASS gi photometry, before the Gala second data release became available, These stars were observed with the SOPHIE spectrograph at the 1.93 in telescope of Observatoire de Haute Provence and we used photometry and parallaxes from Gaia DR2 to derive their atmospheric parameters. Chemical abundances were determined from the spectra for 40 stars of the sample. Eight stars were confirmed to be very metal-poor ([Fe/H] < -2.0), as expected from the photometric estimate. No star was found with [Fe/H] < -3.0, although for nine stars the photometric estimate was below this value. Three multiple systems are identified from their multipeaked cross-correlation functions, Two metal-poor stars with [Fe/H] approximate to -1.0 have an age estimate of about 4 Gyr. Accretion from a satellite galaxy is a possible explanation for these 'young metal-poor stars', but they could also be field blue stragglers. Galactic orbits for our sample of stars allowed us to divide them into three classes that we label 'Halo', 'Thick', and 'Thin' and tentatively identify as halo, thick disc, and thin disc. We present a new method for deriving photometric metallicities, effective temperatures, and surface gravities by combining Gala parallaxes, photometry, and Pristine CaHK photometry. Comparison with spectroscopic metallicities shows a very good agreement and suggests that we can further improve the efficiency of Pristine CaHK in selecting metal poor stars.

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Type
research article
DOI
10.1093/mnras/stz1378
Web of Science ID

WOS:000478053200063

Author(s)
Bonifacio, P.
Caffau, E.
Sestito, F.
Lardo, C.  
Martin, N. F.
Starkenburg, E.
Sbordone, L.
Francois, P.
Jablonka, P.  
Henden, A. A.
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Date Issued

2019-08-01

Publisher

OXFORD UNIV PRESS

Published in
Monthly Notices Of The Royal Astronomical Society
Volume

487

Issue

3

Start page

3797

End page

3814

Subjects

Astronomy & Astrophysics

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stars: abundances

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stars: atmospheres

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stars: kinematics and dynamics

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stars: population ii

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galaxy: abundances

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galaxy: evolution

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metal-poor stars

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ca-ii h

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uvby-beta photometry

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deficient red giants

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k-filter photometry

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digital sky survey

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high-velocity

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milky-way

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chemical abundances

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lithium abundance

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASTRO  
Available on Infoscience
August 14, 2019
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/159766
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