J/A+A/699/A163 Pristine Inner Galaxy Survey (PIGS). XI, (Vitali+, 2025)
The Pristine Inner Galaxy Survey (PIGS).
XI: Revealing the chemical evolution of the interacting Sagittarius dwarf.
Vitali S., Rojas-Arriagada A., Jofre P., Sestito F., Povick J., Povick J.,
Hill V., Fernandez-Alvar E., Ardern-Arentsen A., Jablonka P., Martin N.F.,
Starkenburg E., Aguado D.
<Astron. Astrophys. 699, A163 (2025)>
=2025A&A...699A.163V 2025A&A...699A.163V (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Populations, stellar ; Abundances ; Optical
Keywords: techniques: spectroscopic - stars: abundances - stars: Population II -
galaxies: abundances - galaxies: dwarf
Abstract:
The Sagittarius dwarf spheroidal galaxy (Sgr dSph) is a satellite
orbiting the Milky Way that has experienced multiple stripping events
due to tidal interactions with our Galaxy. Its accretion history has
led to a distinct stellar overdensity, which is the remnant of the
core of the progenitor.
We present a complete chemical analysis of 111 giant stars in the core
of Sgr dSph to investigate the chemical evolution and enrichment
history of this satellite.
Employing the metallicity-sensitive Ca H&K photometry from the
Pristine Inner Galaxy Survey, we selected stars spanning a wide
metallicity range and obtained high-resolution spectra with the ESO
FLAMES/GIRAFFE multi-object spectrograph. For the stellar sample
covering -2.13<[Fe/H]←0.35, we derived abundances for up to 14
chemical elements with average uncertainties of around 0.09dex and a
set of stellar ages which allowed us to build an age-metallicity
relation (AMR) for the entire sample.
With the most comprehensive set of chemical species measured for the
core of Sgr (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ba, La and Eu), we
studied several [X/Fe] ratios. Most trends align closely with Galactic
chemical trends, but notable differences emerge in the heavy n-capture
elements, which offer independent insights into the star formation
history of a stellar population.
We conclude that the deficiency in the alpha-elements with respect the
Milky Way suggests a slower, less efficient early star formation
history, similar to other massive satellites. S-process element
patterns indicate significant enrichment from AGB stars over time. The
AMR and chemical ratios point to an extended star formation history,
with a rapid early phase in the first Gyr, followed by declining
activity and later star-forming episodes. These findings are
consistent with Sgr hosting multiple stellar populations, from young
(around 4 Gyr) to old, metal-poor stars (around 10 Gyr).
Description:
In this work, we provide the largest high-resolution optical data-set
for the core of Sgr and we measured 14 different chemical elements,
shedding light on the chemical evolution history of this system. The
sample was observed with the ESO FLAMES/GIRAFFE multi-object
spectrograph.
The targets were previously observed with the the wide-field imager
MegaCam on the Canada-France-Hawaii Telescope (CFHT) with the Pristine
Inner Galaxy survey (Arentsen et al., 2020MNRAS.496.4964A 2020MNRAS.496.4964A).
Reddening from Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S) and updated by
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 215 111 Coordinates, stellar parameters of the targets
and IDs
table3_1.dat 28 51 Line selection for chemical abundances
table3_2.dat 55 764 Final abundances in bracket notation for
each element
table3_3.dat 22 14 Absolute solar abundances for each element
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/MNRAS/530/3391 : Pristine Inner Galaxy Survey. VIII. (Ardern-Arentsen+, 2024)
J/A+A/689/A201 : Pristine Inner Galaxy Survey. IX. (Sestito+, 2024)
J/A+A/690/A333 : Pristine Inner Galaxy Survey. X. (Sestito+, 2024)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- --- [Gaia DR3]
10- 28 I19 --- GaiaDR3 Gaia DR3 source ID
30- 45 F16.13 --- SNR Signal-to-noise ratio
47- 61 F15.11 deg RAdeg Right Ascension (J2000)
63- 77 F15.11 deg DEdeg Declination (J2000)
79- 87 F9.6 mag Gmag Gaia G-band magnitude
89- 98 F10.6 km/s RV Radial velocity
100-103 F4.2 km/s e_RV Uncertainty in radial velocity
105-115 F11.6 K Teff Effective temperature
117-128 F12.8 K e_Teff Uncertainty in effective temperature
130-141 F12.10 [cm/s2] logg Surface gravity
143-155 F13.11 [cm/s2] e_logg Uncertainty in log g
157-174 F18.15 [-] [Fe/H] Metallicity [Fe/H]
176-180 F5.3 [-] e_[Fe/H] Uncertainty in [Fe/H]
182-197 F16.14 km/s vmic Microturbulence velocity
199-215 F17.15 km/s e_vmic Uncertainty in vmic
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Byte-by-byte Description of file: table3_1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Element Chemical element and ionization stage
(e.g., Fe 1)
7- 14 F8.4 nm lambda Wavelength peak
17- 21 F5.3 eV Elow Lower excitation potential of the transition
23- 28 F6.3 [-] loggf Logarithm of the product of the oscillator
strength of the transition
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Byte-by-byte Description of file: table3_2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 source ID (1)
20- 22 A3 --- --- [_ID]
24- 27 A4 --- Element Chemical element and ionization stage
29- 51 E23.15 [-] [X/Fe] Elemental abundance ratio [X/Fe]
52- 55 F4.2 [-] e_[X/Fe] Uncertainty in [X/Fe]
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Note (1): Star identifier is Gaia DR3 source ID + "_ID".
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Byte-by-byte Description of file: table3_3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Star [Sun] Star name
5- 8 A4 --- Element Chemical element and ionization stage
(e.g., "Fe 1")
11- 14 F4.2 [-] AX Absolute abundance of element X
16- 19 F4.2 [-] e_AX Uncertainty in the abundance A_X
21- 22 I2 --- Nlines Number of spectral lines used in the
abundance determination
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Acknowledgements:
Sara Vitali, sara.vitali(at)mail.udp.cl
References:
Arentsen et al., Paper I 2020MNRAS.491L..11A 2020MNRAS.491L..11A
Arentsen et al., Paper II 2020MNRAS.496.4964A 2020MNRAS.496.4964A
Arentsen et al., Paper III 2021MNRAS.505.1239A 2021MNRAS.505.1239A
Vitali et al., Paper IV 2022MNRAS.517.6121V 2022MNRAS.517.6121V
Sestito et al., Paper V 2023MNRAS.518.4557S 2023MNRAS.518.4557S
Zhao et al., Paper VI 2023MNRAS.519..754Z 2023MNRAS.519..754Z
Mashonkina et al., Paper VII 2023MNRAS.523.2111M 2023MNRAS.523.2111M
Ardern-Arentsen et al., Paper VIII 2024MNRAS.530.3391A 2024MNRAS.530.3391A, Cat. J/MNRAS/530/3391
Sestito et al., Paper IX 2024A&A...689A.201S 2024A&A...689A.201S, Cat. J/A+A/689/A201
Sestito et al., Paper X 2024A&A...690A.333S 2024A&A...690A.333S, Cat. J/A+A/690/A333
(End) Patricia Vannier [CDS] 19-May-2025