J/MNRAS/519/5554 Pristine survey. XX. (Arentsen+, 2023)
The Pristine survey.
XX. GTC follow-up observations of extremely metal-poor stars identified from
Pristine and LAMOST.
Arentsen A., Aguado D.S., Sestito F., Gonzalez-Hernandez J.I., Martin N.F.,
Starkenburg E., Jablonka P., Yuan Z.
<Mon. Not. R. Astron. Soc. 519, 5554-5566 (2023)>
=2023MNRAS.519.5554A 2023MNRAS.519.5554A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient ; Radial velocities ; Abundances ;
Effective temperatures ; Photometry, SDSS ; Stars, distances
Keywords: techniques: spectroscopic - stars: chemically peculiar -
stars: Population II - Galaxy: halo
Abstract:
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 survey with the
low-resolution spectroscopic LAMOST database, and re- analysed all
LAMOST spectra with [Fe/H]Pristine←2.5. We find that ∼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 (S/N) spectra, we selected eleven 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 OSIRIS on the 10.4m 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
uncover them more efficiently and confidently.
Description:
Pristine metal-poor candidate LAMOST spectra were re-analysed with a
dedicated metal-poor analysis tool (FERRE). A long list of extremely
metal-poor candidates are available in the first table. The other
three tables correspond to eleven promising stars that were followed
up with OSIRIS, and contain the relevant information for those stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 297 533 *EMP candidates from Pristine and LAMOST
table2.dat 111 11 Summary of OSIRIS observations
table3.dat 502 11 Orbital properties of the OSIRIS sample
table4.dat 51 11 Stellar parameters of the OSIRIS sample
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Note on table1.dat: Figures with spectral fits corresponding to each of the
entries in this table are available in the supplementary materials at MNRAS.
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
J/AN/338/686 : Pristine survey II. Bright stars abundances (Caffau+, 2017)
J/MNRAS/472/2963 : Metallicities of Pristine stars (Youakim+, 2017)
J/MNRAS/487/3797 : A bright star sample observed with SOPHIE (Bonifacio+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 38 A38 --- LAMOST Name of the LAMOST spectrum analysed
40- 54 F15.11 deg RAdeg Right ascension (ICRS) at Ep=2016.0
from Gaia DR3
56- 69 F14.11 deg DEdeg Declination (ICRS) at Ep=2016.0
from Gaia DR3
71- 89 I19 --- GaiaDR3 Gaia DR3 source_id
91-108 F18.13 K TeffFERRE Effective temperature from FERRE
110-130 F21.15 K e_TeffFERRE ?=-999.999 Uncertainty in the effective
temperature
132-149 F18.16 [cm/s2] loggFERRE Surface gravity from FERRE
151-171 F21.16 [cm/s2] e_loggFERRE ?=-999.999 Uncertainty in the
surface gravity
173-191 F19.16 [-] [Fe/H]FERRE Metallicity [Fe/H] from FERRE
193-213 F21.16 [-] e_[Fe/H]FERRE ?=-999.999 Uncertainty in [Fe/H]
215-233 F19.16 [-] [C/Fe]FERRE ?=-1.0 Carbon abundance [C/Fe] from FERRE
235-256 F22.16 [-] e_[C/Fe]FERRE ?=-999.999 Uncertainty in [C/Fe]
258-277 F20.16 --- SNRFERRE Signal-to-noise ratio
279-297 F19.16 [-] logchi2FERRE Chi squared of the fit
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Star Designation assigned in this work (LPNN)
6- 24 A19 --- LAMOST LAMOST designation (JHHMMSS.ss+DDMMSS.s)
26- 44 I19 --- GaiaDR3 Gaia DR3 source_id
46- 47 I2 h RAh Right Ascension (J2000)
49- 50 I2 min RAm Right Ascension (J2000)
52- 56 F5.2 s RAs Right Ascension (J2000)
57 A1 --- DE- Declination sign (J2000)
58- 59 I2 deg DEd Declination (J2000)
61- 62 I2 arcmin DEm Declination (J2000)
64- 67 F4.1 arcsec DEs Declination (J2000)
69- 73 F5.2 mag umag SDSS u-band magnitude
75- 79 F5.2 mag gmag SDSS g-band magnitude
81- 84 I4 s ExpTime total exposure time
86- 87 I2 --- SN392 Signal-to-noise at 392nm
89- 91 I3 --- SN450 Signal-to-noise at 450nm
93 I1 --- Nobs [1/4] Number of observation
95-111 A17 --- Obs.Date Observation date(s)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Star Designation assigned in this work (LPNN)
6- 12 F7.2 km/s RV Radial velocity
14- 15 I2 km/s e_RV Radial velocity uncertainty
17- 21 F5.2 kpc Dist Distance
23- 26 F4.2 kpc e_Dist Distance uncertainty
28- 31 F4.2 --- pDist Probability of distance solution
33- 51 F19.16 kpc zmax Maximum distance from the Milky Way plane
53- 71 F19.16 kpc E_zmax Positive asymmetric zmax uncertainty
73- 91 F19.16 kpc e_zmax Negative asymmetric zmax uncertainty
93-110 F18.15 kpc apo Apocentric distance
112-131 F20.16 kpc E_apo Positive asymmetric apo uncertainty
133-151 F19.16 kpc e_apo Negative asymmetric apo uncertainty
153-171 F19.16 kpc peri Pericentric distance
173-190 F18.16 kpc E_peri Positive asymmetric peri uncertainty
192-209 F18.16 kpc e_peri Negative asymmetric peri uncertainty
211-228 F18.16 --- ell Ellipticity
230-247 F18.16 --- E_ell Positive asymmetric ell uncertainty
249-266 F18.16 --- e_ell Negative asymmetric ell uncertainty
268-286 F19.12 kpc.km2/s2 E Energy
288-306 F19.13 kpc.km2/s2 E_E Positive asymmetric E uncertainty
308-326 F19.13 kpc.km2/s2 e_E Negative asymmetric E uncertainty
328-347 F20.14 kpc.km/s jp J_phi action
349-366 F18.14 kpc.km/s E_jp Positive asymmetric jp uncertainty
368-385 F18.14 kpc.km/s e_jp Negative asymmetric jp uncertainty
387-404 F18.14 kpc.km/s jr J_r action
406-423 F18.14 kpc.km/s E_jr Positive asymmetric jr uncertainty
425-443 F19.15 kpc.km/s e_jr Negative asymmetric jp uncertainty
445-463 F19.14 kpc.km/s jz J_z action
465-483 F19.15 kpc.km/s E_jz Positive asymmetric jr uncertainty
485-502 F18.14 kpc.km/s e_jz Negative asymmetric jr uncertainty
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Star Designation assigned in this work (LPNN)
6- 9 I4 K Teff Effective temperature from FERRE
11- 13 I3 K e_Teff Uncertainty in Teff
15- 18 F4.2 [cm/s2] logg Surface gravity from FERRE
20- 23 F4.2 [cm/s2] e_logg Uncertainty in logg
25- 29 F5.2 [-] [Fe/H] Metallicity [Fe/H] from FERRE
31- 34 F4.2 [-] e_[Fe/H] Uncertainty in [Fe/H]
36 A1 --- l_[C/Fe] Limit flag on [C/Fe]
37- 41 F5.2 [-] [C/Fe] Carbon abundance [C/Fe] from FERRE (1)
43- 46 F4.2 [-] e_[C/Fe] ? Uncertainty in [C/Fe]
48- 51 F4.2 --- Corr ? Evolutionary carbon correction (according to
Placco et al., 2014ApJ...797...21P 2014ApJ...797...21Pi,
Cat. J/ApJ/797/21)
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Note (1): Solar carbon abundance adopted from Asplund et al.
(2005ASPC..336...25A 2005ASPC..336...25A)
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Acknowledgements:
Anke Arentsen, anke.arentsen(at)ast.cam.ac.uk
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(End) Patricia Vannier [CDS] 18-Jan-2023