J/A+A/687/A177 Metallicities for 10861062 stars (Xylakis-Dornbusch+, 2024)
Metallicities for more than 10 million stars derived from Gaia BP/RP spectra.
Xylakis-Dornbusch T., Christlieb N., Hansen T.T., Nordlander T.,
Webber K.B., Marshall J.
<Astron. Astrophys. 687, A177 (2024)>
=2024A&A...687A.177X 2024A&A...687A.177X (SIMBAD/NED BibCode)
ADC_Keywords: Stars, population II ; Stars, metal-deficient ; Surveys ;
Abundances, [Fe/H]
Keywords: catalogs - surveys - stars: population II
Abstract:
The third Gaia Data Release, which includes BP/RP spectra for 219
million sources, has opened a new window in the exploration of the
chemical history and evolution of the Milky Way. The wealth of
information encapsulated in these data is far greater than their low
resolving power (R ∼ 50) at first glance would suggest, as shown in
many studies. We zero in on the use of this data for the purpose of
the detection of "new" metal-poor stars, which are hard to find yet
essential for understanding - among other - several aspects of the
origin of the Galaxy, star formation and the creation of the elements.
We strive to refine a metal-poor candidate selection method which was
developed with simulated Gaia BP/RP spectra, with an ultimate
objective of providing the community with both a recipe to select
stars for medium/high resolution observations and a catalogue of
stellar metallicities.
We used a dataset comprised of GALAH DR3 and SAGA database stars in
order to verify and adjust to real world data our selection method.
For that purpose, we used dereddening as a mean to tackle the issue of
extinction, and then we applied our fine-tuned method to select
metal-poor candidates, which we thereafter observed and analysed.
We were able to infer metallicities for GALAH DR3 and SAGA stars -
with color excesses up to E(B-V)<1.5 - with an uncertainty of
σ[Fe/H]inf∼0.36, which is good enough for the purpose of
identifying new metal-poor stars. Further, we selected 26 metal-poor
candidates - via our method - for observations. As spectral analysis
showed, 100% of them had [Fe/H]←2.0, 57% had [Fe/H]←2.5 and 8%
had [Fe/H]←3.0. We inferred metallicities for these stars with an
uncertainty σ[Fe/H]inf∼0.31, as was proven when comparing to
the spectroscopic [Fe/H]. Finally, we assembled a catalogue of
metallicities for 10861062 stars.
Description:
We applied the metal-poor star candidate selection recipe described in
Paper I (Xylakis-Dornbusch et al., 2022A&A...666A..58X 2022A&A...666A..58X, Cat.
J/A+A/666/A58) to Gaia DR3 BP/RP spectra.
Metallicities ([Fe/H]) for 10861062 stars, which were derived from
Gaia BP/RP spectra, are presented. For each source the Gaia source id,
RA, DEC, E(B-V), frCaHK/Hβ, frG/CaNIR, [Fe/H]inf, G, G_BP, and
G_RP magnitudes are given.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 204 10861062 Inferred [Fe/H], Gaia DR3 identifier, positions,
and magnitudes for 10861062 stars (table 3)
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/MNRAS/506/150 : The GALAH+ Survey DR3 (Buder+, 2021)
J/A+A/666/A58 : Metal-poor stars identification method
(Xylakis-Dornbusch+, 2022)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- Seq [0/10861061] Sequential number
10- 28 I19 --- GaiaDR3 Gaia DR3 source id
30- 51 E22.20 deg RAdeg Right ascension (ICRS) at Ep=2016.0
53- 75 E23.20 deg DEdeg Declination (ICRS) at Ep=2016.0
77- 97 F21.19 mag E(B-V) Color excess (1)
99-120 E22.20 --- frCaHK/Hb Flux-ratio CaHK/Hβ
122-139 F18.16 --- frG/CaNIR Flux-ratio C/CaNIR
141-147 F7.3 --- [Fe/H]inf Inferred [Fe/H]
149-166 F18.15 mag Gmag G Gaia magnitude
168-185 F18.15 mag BPmag BP Gaia magnitude
187-204 F18.15 mag RPmag RP Gaia magnitude
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Note (1): The color excess values, E(B-V), are taken from Schlegel et al.
(1998ApJ...500..525S 1998ApJ...500..525S) (re-calibrated by Schlafly & Finkbeiner
(2011ApJ...737..103S 2011ApJ...737..103S).
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Acknowledgements:
Theodora Xylakis-Dornbusch, txylaki(at)lsw.uni-heidelberg.de
References:
Xylakis-Dornbusch et al., Paper I 2022A&A...666A..58X 2022A&A...666A..58X, Cat. J/A+A/666/A58
(End) T. Xylakis-Dornbusch [LSW/ZAH, Heidelberg], P. Vannier [CDS] 18-Jun-2024