J/A+A/683/L11 Bright VPM stars from Gaia RVS spectra (Viswanathan+, 2024)
Gaia's brightest very metal-poor (VMP) stars: Metallicity catalogue of a
thousand VMP stars from Gaia's radial velocity spectrometer spectra.
Viswanathan A., Starkenburg E., Matsuno T., Venn K.A., Martin N.F.,
Longeard N., Ardern-Arentsen A., Carlberg R.G., Fabbro S., Kordopatis G.,
Montelius M., Sestito F., Yuan Z.
<Astron. Astrophys. 683, L11 (2024)>
=2024A&A...683L..11V 2024A&A...683L..11V (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, metal-deficient ; Abundances, [Fe/H] ;
Equivalent widths
Keywords: method: data analysis - techniques: spectroscopic -
stars: chemically peculiar - stars: Population II - Galaxy: halo -
Galaxy: stellar content
Abstract:
Gaia DR3 has offered the scientific community a remarkable dataset of
approximately one million spectra acquired with the Radial Velocity
Spectrometer (RVS) in the Calcium II triplet region, that is
well-suited to identify very metal-poor (VMP) stars. However, over 40%
of these spectra have no released parameters by Gaia's GSP-Spec
pipeline in the domain of VMP stars, whereas VMP stars are key tracers
of early Galactic evolution. We aim to provide spectroscopic
metallicities for VMP stars using Gaia RVS spectra, thereby producing
a catalogue of bright VMP stars distributed over the full sky that can
serve as the basis to study early chemical evolution throughout the
Galaxy. We select VMP stars using photometric metallicities from the
literature and analyse the Gaia RVS spectra to infer spectroscopic
metallicities for these stars. The inferred metallicities agree very
well with literature high-resolution metallicities with a median
systematic offset of 0.1dex and standard deviation of ∼0.15dex. The
purity of this sample in the VMP regime is ∼80% with outliers
representing a mere ∼3%. We make available an all-sky catalogue of
∼1500 stars with reliable spectroscopic metallicities down to
[Fe/H]~-4.0, of which ∼1000 are VMP stars. More than 75% of these
stars have either no spectroscopic metallicity value in the literature
to date or are flagged to be unreliable in their literature
spectroscopic metallicity estimates. This catalogue of bright (G<13)
VMP stars is three times larger than the current sample of
well-studied VMP stars in the literature in this magnitude range,
making it ideal for high-resolution spectroscopic follow-up and to
study the properties of VMP stars in different parts of our Galaxy.
Description:
Catalogue of very metal-poor stars selected and analysed using the
Gaia DR3 RVS spectra. This table consists of the following columns:
DR3/EDR3 source_ids of sources, positions in equatorial coordinates
(RA, Dec in degrees) in J2016 format, Gaia G, BP, and RP magnitudes,
parallax and parallax uncertainty from Gaia DR3 (parallax,
parallax_error in mas), signal-to-noise ratio of the renormalised Gaia
RVS spectra, radial velocity offset from the rest frame and its
uncertainty (v_offset and dv_offset in km/s), equivalent widths of the
three Calcium Triplet lines and errors on them (in nm), inferred
spectroscopic metallicities and errors on them.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 370 1441 Gaia RVS VMP catalogue (table 1)
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id
21- 40 F20.16 deg RAdeg Right ascension (ICRS) at Ep=2026.0
42- 61 F20.16 deg DEdeg Declination (ICRS) at Ep=2026.0
63- 80 F18.15 mag G0mag Gaia G magnitude corrected for extinction
82- 99 F18.15 mag BP0mag Gaia BP magnitude corrected for extinction
101-118 F18.15 mag RP0mag Gaia RP magnitude corrected for extinction
120-125 F6.4 mas plx Gaia parallax
127-132 F6.4 mas e_plx Gaia parallax error
134-151 F18.14 --- snr SNR of Gaia RVS spectra
153-176 E24.16 km/s voffset Velocity offset from rest frame correction
178-195 F18.16 km/s e_voffset Uncertainty on velocity offset from rest
frame correction
197-214 F18.16 nm EW1 Equivalent width of Ca triplet line 1
216-239 E24.16 nm e_EW1 Error on equivalent width of Ca triplet line 1
241-258 F18.16 nm EW2 Equivalent width of Ca triplet line 2
260-283 E24.16 nm e_EW2 Error on equivalent width of Ca triplet line 2
285-302 F18.16 nm EW3 Equivalent width of Ca triplet line 3
304-327 E24.16 nm e_EW3 Error on equivalent width of Ca triplet line 3
329-349 F21.18 [-] [Fe/H] Spectroscopic metallicity
351-370 F20.18 [-] e_[Fe/H] ?=- Measurement error on spectroscopic
metallicity
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Acknowledgements:
Akshara Viswanathan, viswanathan(at)astro.rug.nl
(End) Patricia Vannier [CDS] 17-Jan-2024