J/MNRAS/472/2963 Metallicities of Pristine stars (Youakim+, 2017)
The Pristine survey. III. Spectroscopic confirmation of an efficient search for
extremely metal-poor stars.
Youakim K., Starkenburg E., Aguado D.S., Martin N.F., Fouesneau M.,
Gonzalez Hernandez J.I., Allende Prieto C., Bonifacio P., Gentile M.,
Kielty C., Cote P., Jablonka P., McConnachie A., Sanchez Janssen R.,
Tolstoy E., Venn K.
<Mon. Not. R. Astron. Soc., 472, 2963-2974 (2017)>
=2017MNRAS.472.2963Y 2017MNRAS.472.2963Y (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient ; Abundances, [Fe/H] ; Photometry, SDSS
Keywords: stars: abundances - Galaxy: evolution - Galaxy: formation -
Local Group - dark ages, reionization, first stars - early Universe
Abstract:
The Pristine survey is a narrow-band, photometric survey focused
around the wavelength region of the CaII H&K absorption lines,
designed to efficiently search for extremely metal-poor stars. In this
work, we use the first results of a medium-resolution spectroscopic
follow-up to refine the selection criteria for finding extremely
metal-poor stars ([Fe/H]≤-3.0) in the Pristine survey. We consider
methods by which stars can be selected from available broad-band and
infrared photometry plus the additional Pristine narrow-band
photometry. The sample consists of 205 stars in the magnitude range
14<V<18. Applying the photometric selection criteria cuts the sample
down to 149 stars, and from these we report a success rate of 70 per
cent for finding stars with [Fe/H]≤-2.5 and 22 per cent for finding
stars with [Fe/H]≤-3.0. These statistics compare favourably with
other surveys that search for extremely metal-poor stars, namely an
improvement by a factor of ∼4-5 for recovering stars with
[Fe/H]≤-3.0. In addition, Pristine covers a fainter magnitude range
than its predecessors and can thus probe deeper into the Galactic
halo.
Description:
In conjunction with the photometric component of Pristine, a
spectroscopic follow-up programme has been observing the most
promising, bright (V<18) metal-poor candidates on 2-4m class
telescopes with medium- and high-resolution spectrographs. In this
paper, we focus on the homogeneous follow-up sample of 205 candidate
stars observed with the Intermediate Dispersion Spectrograph (IDS) on
the 2.5m Isaac Newton Telescope (INT) over the period of 2016 March
18-27, May 15-23, July 20-24 and September 2-6, and with the
Intermediate dispersion Spectrograph and Imaging System (ISIS) on the
4.2m William Herschel Telescope (WHT) over the period of 2016 May
1-2 and July 29-31 (Programs C71 and N5). Both telescopes are
located at the Roque de Los Muchachos Observatory in La Palma, Canary
Islands.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 205 Metallicities of Pristine stars from photometry
and spectroscopy
table1s.dat 96 205 All objects from Table 1 with their SDSS
coordinates and magnitudes used in the paper
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See also:
J/AN/338/686 : Pristine survey II. Bright stars abundances (Caffau+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- --- [Pristine]
10- 25 A16 --- Pristine Pristine designation (DDD.dddd+DD.dddd)
27- 31 F5.2 mag CaHK Magnitude obtained from the Pristine
narrow-band filter
33- 36 F4.2 mag e_CaHK rms uncertainty on CaHK
38- 42 F5.1 [-] [Fe/H]g-i ?=-99 Photometric metallicity
determined using the g-i colour
44- 48 F5.2 --- P[Fe/H]g-i ?=-0.01 Probability that [Fe/H]_g-i≤-2.5
50- 54 F5.1 [-] [Fe/H]g-r ?=-99 Photometric metallicity
determined using the g-r colour
56- 60 F5.2 --- P[Fe/H]g-r ?=-0.01 Probability that [Fe/H]_g-r≤-2.5
62- 63 A2 --- l_[Fe/H] [≥ ] Limit flag on [Fe/H]
64- 67 F4.1 [-] [Fe/H] Spectroscopic metallicity derived form FERRE
69- 71 F3.1 [-] e_[Fe/H] ? rms uncertainty on [Fe/H]
73- 74 I2 --- S/N Signal to noise ratio of the analyzed
spectrum
76- 79 A4 --- Inst Instrument used for the observations,
either INT/IDS or WHT/ISIS
81- 90 A10 --- Flags Selection criteria a given star failed to
meet (1)
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Note (1): Selection criteria as follows:
1 = P([Fe/H]g-r≤-2.5)<0.25 and P([Fe/H]g-i≤-2.5)<0.25
2 = g-band phot flag
3 = point source flag (CASU flag) different of -1
5 = i-band phot flag and P([Fe/H]g-r≤ 2.5)<0.25
6 = [Fe/H]g-i=-99 and P([Fe/H]g-r≤-2.5)<0.25
7 = [Fe/H]g-r=-99 and P([Fe/H]g-i≤-2.5)<0.25
8 = [Fe/H]g-r=-99 and [Fe/H]g-i=-99
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Byte-by-byte Description of file: table1s.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- --- [Pristine]
10- 25 A16 --- Pristine Pristine designation (DDD.dddd+DD.dddd)
27- 28 I2 h RAh SDSS right ascension (J2000)
30- 31 I2 min RAm SDSS right ascension (J2000)
33- 37 F5.2 s RAs SDSS right ascension (J2000)
39 A1 --- DE- SDSS declination sign (J2000)
40- 41 I2 deg DEd SDSS declination (J2000)
43- 44 I2 arcmin DEm SDSS declination (J2000)
46- 50 F5.2 arcsec DEs SDSS declination (J2000)
52- 57 F6.3 mag gmag SDSS g magnitude
59- 63 F5.3 mag e_gmag SDSS g magnitude error
65- 70 F6.3 mag rmag SDSS r magnitude
72- 76 F5.3 mag e_rmag SDSS r magnitude error
78- 83 F6.3 mag imag SDSS i magnitude
85- 89 F5.3 mag e_imag SDSS i magnitude error
91- 96 F6.3 mag Vmag V magnitude (1)
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Note (1): The V-band magnitudes are computed from
https://www.sdss3.org/dr8/algorithms/sdssUBVRITransform.php (Lupton 2005).
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History:
From electronic version of the journal
References:
Starkenburg et al., Paper I 2017MNRAS.471.2587S 2017MNRAS.471.2587S
Caffau et al., Paper II 2017AN....338..686C 2017AN....338..686C, Cat. J/AN/338/686
Starkenburg et al., Paper IV 2018MNRAS.481.3838S 2018MNRAS.481.3838S
(End) Patricia Vannier [CDS] 26-Jun-2020