J/A+A/691/A284 Earliest phases of CNO enrichment in galaxies (Rossi+, 2024)
The earliest phases of CNO enrichment in galaxies.
Rossi M., Romano D., Mucciarelli A., Ceccarelli E., Massari D., Zamorani G.
<Astron. Astrophys. 691, A284 (2024)>
=2024A&A...691A.284R 2024A&A...691A.284R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Abundances ; Stars, halo ; Stars, metal-deficient ;
Effective temperatures ; Abundances
Keywords: stars: abundances - stars: Population III - galaxy: halo -
galaxies: abundances - galaxies: evolution - galaxies: high-redshift
Abstract:
The recent detection of super-solar carbon-to-oxygen and
nitrogen-to-oxygen abundance ratios in a bunch of metal-poor galaxies
at high redshift by the James Webb Space Telescope has sparked renewed
interest in exploring the chemical evolution of carbon, nitrogen, and
oxygen (the CNO elements) at early times, prompting fresh inquiries
into their origins.
The main goal of this paper is to shed light onto the early evolution
of the main CNO isotopes in our Galaxy and in young distant systems,
such as GN-z11 at z=10.6 and GS-z12 at z=12.5.
To this aim, we incorporate a stochastic star-formation component into
a chemical evolution model calibrated with high quality Milky Way (MW)
data, focusing on the contribution of Population III (Pop III) stars
to the early chemical enrichment.
By comparing the model predictions with CNO abundance measurements
from high-resolution spectroscopy of an homogeneous sample of Galactic
halo stars, we first demonstrate that the scatter observed in the
metallicity range -4.5≤[Fe/H]≤-1.5 can be explained by
pre-enrichment from Pop III stars that explode as supernovae (SNe)
with different initial masses and energies. Then, by exploiting the
chemical evolution model, we provide testable predictions for
log(C/N), log(N/O), and log(C/O) vs. log(O/H)+12 in MW-like galaxies
observed at different cosmic epochs/redshifts. Finally, by calibrating
the chemical evolution model to replicate the observed properties of
GN-z11 and GS-z12, we provide an alternative interpretation of their
high N/O and C/O abundance ratio, respectively, demonstrating that an
anomalously high N or C content can be reproduced through enrichment
from faint Pop III SNe.
Stochastic chemical enrichment from primordial stars explains both the
observed scatter in CNO abundances in MW halo stars and the
exceptionally high C/O and N/O ratios in some distant galaxies. These
findings emphasize the critical role of Pop III stars in shaping early
chemical evolution.
Description:
Abundances of CNO elements are homogeneously derived for the sample of
lower RGB halo stars presented in Mucciarelli et al.
(2022A&A...661A.153M 2022A&A...661A.153M, Cat. J/A+A/661/A153). After a careful evaluation
of all possible systematics, we complement this sample with the one of
Yong et al. (2013ApJ...762...26Y 2013ApJ...762...26Y, Cat. J/ApJ/762/26). Abundance
estimates for dwarf stars from three dimensional (3D) radiative
transfer calculations including corrections for non local
thermodynamic equilibrium (non-LTE) conditions (Amarsi et al.,
2019A&A...630A.104A 2019A&A...630A.104A) are added for comparison. We further derive the
orbital parameters of the program stars to distinguish those born in
situ from the accreted ones (Sect. 2.1.3) and to identify the
different progenitors of the latter.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 103 74 ID, stellar parameters and chemical abundances
of the unmixed halo stars
table2.dat 99 74 Orbital parameters
--------------------------------------------------------------------------------
See also:
J/ApJ/762/26 : Most metal-poor stars. II. 190 Galactic halo stars
(Yong+, 2013)
J/A+A/661/A153 : Metal-poor red giant branch stars (Mucciarelli+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
18- 36 I19 --- GaiaDR3 Gaia DR3 identifier
38- 41 I4 K Teff Effective temperature
43- 47 F5.2 [cm/s2] logg Effective temperature error
50- 54 F5.2 --- [Fe/H] Metallicity, [Fe/H]
56- 59 F4.2 --- e_[Fe/H] ? Metallicity, [Fe/H], error
61 A1 --- l_[C/Fe] Limit flag on [C/Fe]
62- 66 F5.2 --- [C/Fe] Abundance [C/Fe]
68- 71 F4.2 --- e_[C/Fe] ? Abundance [C/Fe] error
74- 78 F5.2 --- [N/Fe] ?=- Abundance [N/Fe]
80- 83 F4.2 --- e_[N/Fe] ? Abundance [N/Fe] error
84 A1 --- l_[O/Fe] Limit flag on [O/Fe]
85- 88 F4.2 --- [O/Fe] ?=- Abundance [O/Fe]
90- 93 F4.2 --- e_[O/Fe] ? Abundance [O/Fe] error
95- 98 F4.2 --- [Mg/Fe] ?=- Abundance [Mg/Fe]
100-103 F4.2 --- e_[Mg/Fe] ? Abundance [Mg/Fe] error
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
18- 36 I19 --- GaiaDR3 Gaia DR3 identifier
38- 44 F7.4 10+5km2/s2 E Orbital energy
46- 51 F6.4 10+5km2/s2 e_E Orbital energy error
53- 59 F7.4 10+3kpc.km/s Lz Angular momentum along the z-axis
61- 66 F6.4 10+3kpc.km/s e_Lz Angular momentum along the z-axis error
68- 74 F7.4 10+3kpc.km/s Lperp Perpendicular component of the angular
momentum
76- 82 F7.4 10+3kpc.km/s e_Lperp Perpendicular component of the angular
momentum error
84- 92 F9.4 km/s Vlos Line of-sight velocity
94- 99 F6.4 km/s e_Vlos Line of-sight velocity error
--------------------------------------------------------------------------------
Acknowledgements:
Martina Rossi, martina.rossi(at)inaf.it
(End) Patricia Vannier [CDS] 07-Oct-2024