J/A+A/703/A4 Stellar evolution and age C and N indicators (Tautvaisiene+, 2025)
Carbon and nitrogen as indicators of stellar evolution and age.
A homogeneous sample of 44 open clusters from the Gaia-ESO Survey.
Tautvaisiene G., Drazdauskas A., Mikolaitis S., Minkeviciute R.,
Stonkute E., Randich S., Bragaglia A., Magrini L., Smiljanic R.,
Ambrosch M., Bagdonas V., Casali G., Chorniy Y., Viscasillas Vazquez C.
<Astron. Astrophys. 703, A4 (2025)>
=2025A&A...703A...4T 2025A&A...703A...4T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Abundances ; Radial velocities ;
Effective temperatures ; Spectra, optical
Keywords: stars: abundances - stellar evolution - Galaxy: disk -
open clusters and associations: general
Abstract:
Low- and intermediate-mass giants undergo a complex chemical evolution
that has yet to be observationally probed. The influence of core
helium-flash on the chemical composition of stellar atmospheres is an
open question since its theoretical prediction 60 years ago.
Based on high-resolution spectral observations of 44 open star
clusters in the Gaia-ESO survey, our aim is to perform the first
large-scale homogeneous investigation into the carbon and nitrogen
photospheric content of low- and intermediate-mass giant stars in
different phases of evolution.
Carbon and nitrogen abundances were determined using spectral
synthesis of the C2 Swan (1,0) band head at 5135Å and C2 Swan (0,1)
band head at 5635.5Å, 12C14N bands in the interval
6470-6490Å, and the forbidden [O I] line at 6300.31Å. Results.
We revealed differences in C/N abundance ratios between pre- and
post-core-He-flash stars. The lower C/N ratios in core He-burning red
clump stars are mainly due to the enhancement of nitrogen abundances.
We presented calibrations of the relationship between [C/N] and
stellar age for solar metallicity low- and intermediate-mass giants
taking into account different evolutionary stages.
The C/N abundance ratios in the investigated first-ascent giant stars
are affected by the first dredge-up slightly less than predicted by
the theoretical model of Lagarde et al. (2017A&A...601A..27L 2017A&A...601A..27L ). The
rotation-induced extra-mixing is not as efficient as predicted by the
model of Lagarde et al. ( 2012A&A...543A.108L 2012A&A...543A.108L, Cat. J/A+A/543/A108).
The core helium flash may trigger additional alterations in carbon and
nitrogen abundances that are not yet theoretically modelled. We found
that the evolutionary stage of stars must be taken into account when
using [C/N] as an age indicator.
Description:
We used high-resolution spectral observations of 44 open star clusters
in the Gaia-ESO survey, and performed the homogeneous investigation
into the carbon and nitrogen photospheric content of low- and
intermediate-mass giant stars in different phases of evolution.
Results were compared to extra-mixing models.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 139 327 The names of the investigated OCs
tablea2.dat 191 44 Averaged abundances according evolutionary stages
--------------------------------------------------------------------------------
See also:
J/MNRAS/509/1664 : Membership study of 70 stars clusters (Jackson+, 2022)
J/A+A/686/A42 : Improving the open cluster census. III. (Hunt+, 2024)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Cluster Cluster name
12- 27 A16 --- ID Identification of the star in the cluster,
HHMMSSss+DDMMSSs
29- 34 F6.2 --- SNR Signal-to-noise ratio
36- 39 I4 K Teff Effective temperature
41- 42 I2 K e_Teff Uncertainty in effective temperature
44- 47 F4.2 [cm/s2] logg log of surface gravity
49- 52 F4.2 [cm/s2] e_logg logg uncertainty
54- 58 F5.2 [-] [Fe/H] Metallicity
60- 63 F4.2 [-] e_[Fe/H] Error of metallicity
65- 68 F4.2 km/s Vt Microturbulent velocity
70- 73 F4.2 km/s e_Vt Uncertainty in microturbulence velocity
75- 79 F5.2 [-] [C/H] Carbon abundance
81- 84 F4.2 [-] e_[C/H] Uncertainty in carbon abundance
86- 90 F5.2 [-] [N/H] Nitrogen abundance
92- 95 F4.2 [-] e_[N/H] Uncertainty in nitrogen abundance
97-101 F5.2 [-] [O/H] ? Oxygen abundance
103-106 F4.2 [-] e_[O/H] ? Uncertainty in oxygen abundance
108-111 F4.2 [-] C/N C/N abundance ratio
113-117 A5 [-] Evol Evolutionary stage (1)
119-124 F6.2 km/s RV Radial velocity
126-129 F4.2 km/s e_RV Uncertainty in radial velocity
131-134 F4.2 --- MHR ? Membership probability according to
Hunt & Reffert (2024A&A...686A..42H 2024A&A...686A..42H,
Cat. J/A+A/686/A42)
136-139 F4.2 --- MJ ? Membership probability according to
Jackson et al. (2022MNRAS.509.1664J 2022MNRAS.509.1664J,
Cat. J/MNRAS/509/1664)
--------------------------------------------------------------------------------
Note (1): Evolutionary stage as follows:
BB = below the luminosity bump of RGB
AB = above the luminosity bump of RG
Clump = red clump star
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Cluster Cluster name
12- 16 F5.2 [-] [Fe/H] Metallicity
18- 21 F4.2 Msun MassTO Turn-off mass
23- 26 F4.2 Gyr Age Age
28- 31 F4.2 [yr] logAge log age
33- 37 F5.2 kpc Rgc Galactocentric distance
39- 43 I5 kpc z Maximal distance from the galactic plane
45- 49 F5.2 [-] [O/H] ? Mean oxygen abundance
51- 54 F4.2 [-] e_[O/H] ? Scatter in the mean oxygen abundance
56- 60 F5.2 [-] [C/H]-BB ? Mean carbon abundance in
stars below the RGB luminosity bump
62- 65 F4.2 [-] e_[C/H]-BB ? Scatter of the mean carbon abundance in
stars below the RGB luminosity bump
67- 71 F5.2 [-] [N/H]-BB ? Mean nitrogen abundance in
stars below the RGB luminosity bump
73- 76 F4.2 [-] e_[N/H]-BB ? Scatter of the mean nitrogen abundance in
stars below the RGB luminosity bump
78- 82 F5.2 [-] [C/N]-BB ? Mean [C/N] abundance ratio in
stars below the RGB luminosity bump
84- 87 F4.2 [-] e_[C/N]-BB ? Scatter of the mean [C/N] ratio in
stars below the RGB luminosity bump
89- 92 F4.2 [-] C/N-BB ? Mean C/N abundance ratio in
stars below the RGB luminosity bump
94- 97 F4.2 [-] e_C/N-BB ? Scatter of the mean C/N ratio in
stars below the RGB luminosity bump
99-100 I2 --- No-BB ? Number of stars below RGB luminosity bump
102-106 F5.2 [-] [C/H]-AB ? Mean carbon abundance in
stars above the RGB luminosity bump
108-111 F4.2 [-] e_[C/H]-AB ? Scatter of the mean carbon abundance in
stars above the RGB luminosity bump
113-117 F5.2 [-] [N/H]-AB ? Mean nitrogen abundance in
stars above the RGB luminosity bump
119-122 F4.2 [-] e_[N/H]-AB ? Scatter of the mean nitrogen abundance in
stars above the RGB luminosity bump
124-128 F5.2 [-] [C/N]-AB ? Mean [C/N] abundance ratio in
stars above the RGB luminosity bump
130-133 F4.2 [-] e_[C/N]-AB ? Scatter of the mean [C/N] ratio in
stars above the RGB luminosity bump
135-138 F4.2 [-] C/N-AB ? Mean C/N abundance ratio in
stars above the RGB luminosity bump
140-143 F4.2 [-] e_C/N-AB ? Scatter of the mean C/N ratio in
stars above the RGB luminosity bump
145 I1 --- No-AB ? Number of stars above RGB luminosity bump
147-151 F5.2 [-] [C/H]-clump ? Mean carbon abundance in
red clump stars
153-156 F4.2 [-] e_[C/H]-clump ? Scatter of the mean carbon abundance in
red clump stars
158-162 F5.2 [-] [N/H]-clump ? Mean nitrogen abundance in
red clump stars
164-167 F4.2 [-] e_[N/H]-clump ? Scatter of the mean nitrogen abundance in
red clump stars
169-173 F5.2 [-] [C/N]-clump ? Mean [C/N] abundance ratio in
red clump stars
175-178 F4.2 [-] e_[C/N]-clump ? Scatter of the mean [C/N] ratio in
red clump stars
180-183 F4.2 [-] C/N-clump ? Mean C/N abundance ratio in
red clump stars
185-188 F4.2 [-] e_C/N-clump ? Scatter of the mean C/N ratio in
red clump stars
190-191 I2 --- No-Clump ? Number of red clump stars
--------------------------------------------------------------------------------
Acknowledgements:
From Sarunas Mikolaitis, sarunas.mikolaitis(at)tfai.vu.lt
Based on data products from observations made with ESO Telescopes at
the La Silla Paranal Observatory un der programmes ID 188.B-3002,
193-B-0936, and 197.B-1074. These data products have been processed by
the Cambridge Astronomy Survey Unit (CASU) at the Institute of
Astronomy, University of Cambridge, and by the FLAMES/UVES reduction
team at INAF-Osservatorio Astrofisico di Arcetri. Public access to the
data products is via the ESO Archive, and the Gaia-ESO Survey Data
Archive, prepared and hosted by the Wide Field Astronomy Unit,
Institute for Astronomy, University of Edinburgh, which is funded by
the UK Science and Technology Facilities Council. This work has made
use of data from the European Space Agency (ESA) mission Gaia
(https://www.cosmos.esa.int/gaia), processed by the Gaia Data
Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/ Consortium). Funding for the
DPAC has been provided by national institutions in particular the
institutions participating in the Gaia Multilateral Agreement. We have
made extensive use of the NASA ADS and SIMBAD databases. G.T., A.D.,
S.M., R.M., E.S., M.A., V.B., Y.Ch., and C.V.V. acknowledge funding
from the Research Council of Lithuania (LMTLT, grant No. S-MIP-23-24).
L.M. thanks INAF for the support (Large Grants EPOCH and WST), the
Mini-Grants Checs (1.05.23.04.02), and the financial support under
National Recovery and Resilience Plan (NRRP), Mission 4, Component 2,
Investment 1.1, Call for tender No. 104 published on 2.2.2022 by the
Italian Ministry of the University and Research, funded by the
European Union - NextGenerationEU - Project 'Cosmic POT' Grant
Assignment Decree No. 2022X4TM3H by the Italian Ministry of the
University and Research. G.C. thanks the Mini-Grants Checs
(1.05.23.04.02).
(End) Patricia Vannier [CDS] 02-Sep-2025