J/A+A/690/A333 Pristine Inner Galaxy Survey. X. (Sestito+, 2024)
The Pristine Inner Galaxy Survey (PIGS).
X. Probing the early chemical evolution of the Sagittarius dwarf galaxy with
carbon abundances.
Sestito F., Ardern-Arentsen A., Vitali S., Montelius M., Lucchesi R.,
Venn K.A., Martin N.F., Navarro J.F., Starkenburg E.
<Astron. Astrophys. 690, A333 (2024)>
=2024A&A...690A.333S 2024A&A...690A.333S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, metal-deficient ; Abundances ; Optical ;
Radial velocities ; Effective temperatures
Keywords: stars: abundances - stars: Population II - galaxies: abundances -
galaxies: dwarf - galaxies: individual: Sagittarius
Abstract:
We aim to constrain the chemo-dynamical properties of the Sagittarius
(Sgr) dwarf galaxy using carbon abundances. At low metallicities in
particular, these properties reveal the early chemical evolution of a
system, tracing the contributing supernovae (SNe) and how much of
their ejecta eventually made it into the next stellar generation. Our
sample from the Pristine Inner Galaxy Survey (PIGS) includes ∼350
metal-poor ([Fe/H]←1.5) stars in the main body of Sgr with good
quality spectroscopic observations. Our metalpoor Sgr population has a
larger velocity dispersion than metal-rich Sgr from the literature,
which could be explained by outside-in star formation, extreme
Galactic tidal perturbations, and/or the presence of a metal-rich disc
and bar + metal-poor halo. The average carbon abundance [C/Fe] in Sgr
is similar to that of other classical dwarf galaxies (DGs) and
consistently lower than in the Milky Way by ∼0.2-0.3dex at low
metallicities. The interstellar medium in DGs, including Sgr, may have
retained yields from more energetic Population III and II supernovae
(SNe), thereby reducing the average [C/Fe]. Additionally, SNe Ia
producing more Fe than C would start to contribute at lower
metallicity in DGs/Sgr than in the Galaxy. The presence of a [C/Fe]
gradient for Sgr stars with [Fe/H]≳-2.0 (∼6.8x10-4dex/ arcmin)
suggests that SNe Ia contributed to the system at those metallicities,
especially in its inner regions. There is a low frequency of
carbon-enhanced metal-poor (CEMP) stars in our Sgr sample. At higher
metallicities and carbon abundances (i.e. mostly CEMPs), this may be
due to photometric selection effects, but those are less likely to
affect non-CEMP stars. Given the lower average [C/Fe] in DGs, we
propose using the same CEMP definition ([C/Fe]>+0.7) as that applied
to the Galaxy at large ends up underpredicting the number of CEMP
stars in DGs. Burthermore, for Sgr, a cut at [C/Fe]~+0.35 may be more
appropriate, which brings the frequency of CEMP stars in agreement
with that of the whole Galaxy.
Description:
The chemo-dynamical properties of the low-metallicity regime
of the Sagittarius dwarf galaxy are explored using the low- and
medium-resolution AAT spectra observed by the Pristine Inner Galaxy
Survey (PIGS). The PIGS dataset contains measurements of RVs, stellar
parameters, [Fe/H], and [C/Fe] for stars towards the inner Galaxy and
Sgr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
memb.dat 201 834 *Sgr members using a kinematical selection based
on Gaia
membpara.dat 201 356 Sgr members from PIGS/AAT that have reliable
measurements of metallicity, [C/Fe], and
stellar parameters
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Note on memb.dat: some of the stars do not have reliable measurements of
metallicity and [C/Fe].
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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)
Byte-by-byte Description of file: memb.dat membpara.dat
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Bytes Format Units Label Explanations
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1- 27 A27 --- PIGS Starname with PIGS nomenclature
(Pristine_HHMMSS.ss+DDMMSS.s)
29- 47 A19 --- Field PIGS fieldname (FieldLLL.l+BB.b)
49- 67 I19 --- GaiaDR3 Gaia DR3 source ID
69- 83 F15.11 deg RAdeg Right ascension (J2000)
85- 99 F15.11 deg DEdeg Declination (J2000)
101-108 F8.4 km/s RV Radial velocity
110-115 F6.3 km/s e_RV Radial velocity error
117-124 F8.3 K Teff Effective temperature from FERRE
126-133 F8.3 K e_Teff Effective temperature error from FERRE
135-139 F5.3 [cm/s2] logg Surface gravity from FERRE
141-146 F6.4 [cm/s2] e_logg Surface gravity error from FERRE
148-153 F6.3 [-] [Fe/H] Metallicity from FERRE
155-160 F6.4 [-] e_[Fe/H] Metallicity error from FERRE
162-167 F6.3 [-] [C/Fe] Abundance [C/Fe] from FERRE
169-174 F6.4 [-] e_[C/Fe] Abundance [C/Fe] error from FERRE
176-181 F6.4 [-] [C/Fe]corr ?=- Correction to [C/Fe] as in
Placco et al., 2014ApJ...797...21P 2014ApJ...797...21P,
Cat. J/ApJ/797/21)
183-191 F9.3 mas/yr pmRAred Reduced proper motion on right ascension
193-201 F9.3 mas/yr pmDEred Reduced proper motion on declination
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Acknowledgements:
Federico Sestito, f.sestito(at)herts.ac.uk
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
(End) Patricia Vannier [CDS] 27-Sep-2024