2019A&A...621A..24L

Query : 2019A&A...621A..24L

2019A&A...621A..24L - Astronomy and Astrophysics, volume 621A, 24-24 (2019/1-1)

The Gaia-ESO Survey: impact of extra mixing on C and N abundances of giant stars.

LAGARDE N., REYLE C., ROBIN A.C., TAUTVAISIENE G., DRAZDAUSKAS A., MIKOLAITIS S., MINKEVICIUTE R., STONKUTE E., CHORNIY Y., BAGDONAS V., MIGLIO A., NASELLO G., GILMORE G., RANDICH S., BENSBY T., BRAGAGLIA A., FLACCOMIO E., FRANCOIS P., KORN A.J., PANCINO E., SMILJANIC R., BAYO A., CARRARO G., COSTADO M.T., JIMENEZ-ESTEBAN F., JOFRE P., MARTELL S.L., MASSERON T., MONACO L., MORBIDELLI L., SBORDONE L., SOUSA S.G. and ZAGGIA S.

Abstract (from CDS):


Context. The Gaia-ESO Public Spectroscopic Survey using FLAMES at the VLT has obtained high-resolution UVES spectra for a large number of giant stars, allowing a determination of the abundances of the key chemical elements carbon and nitrogen at their surface. The surface abundances of these chemical species are known to change in stars during their evolution on the red giant branch (RGB) after the first dredge-up episode, as a result of the extra mixing phenomena.
Aims. We investigate the effects of thermohaline mixing on C and N abundances using the first comparison between the Gaia-ESO survey [C/N] determinations with simulations of the observed fields using a model of stellar population synthesis.
Methods. We explore the effects of thermohaline mixing on the chemical properties of giants through stellar evolutionary models computed with the stellar evolution code STAREVOL. We include these stellar evolution models in the Besancon Galaxy model to simulate the [C/N] distributions determined from the UVES spectra of the Gaia-ESO survey and to compare them with the observations.
Results. Theoretical predictions including the effect of thermohaline mixing are in good agreement with the observations. However, the field stars in the Gaia-ESO survey with C and N abundance measurements have a metallicity close to solar, where the efficiency of thermohaline mixing is not very large. The C and N abundances derived by the Gaia-ESO survey in open and globular clusters clearly show the impact of thermohaline mixing at low metallicity, which explains the [C/N] value observed in lower mass and older giant stars. Using independent observations of carbon isotopic ratio in clump field stars and open clusters, we also confirm that thermohaline mixing should be taken into account to explain the behaviour of 12C/13C as a function of stellar age.
Conclusions. Overall, the current model including thermohaline mixing is able to reproduce very well the C and N abundances over the whole metallicity range investigated by the Gaia-ESO survey data.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: abundances - stars: evolution - Galaxy: stellar content - Galaxy: abundances

Simbad objects: 27

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Number of rows : 27
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20     4.09     ~ 3916 0
2 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1429 0
3 NGC 2243 OpC 06 29 34.8 -31 16 55   10.12 9.4     ~ 269 0
4 Cl Berkeley 31 OpC 06 57 37.4 +08 17 06           ~ 128 0
5 NGC 2324 OpC 07 04 07.9 +01 02 46   8.83 8.4     ~ 159 0
6 Cl Berkeley 36 OpC 07 16 25.2 -13 11 46           ~ 41 0
7 Cl Melotte 66 OpC 07 26 17.5 -47 41 06   8.73       ~ 196 0
8 Cl Melotte 71 OpC 07 37 31.9 -12 03 54   7.44 7.1     ~ 130 0
9 NGC 2477 OpC 07 52 11.0 -38 32 13   6.64 5.8     ~ 290 0
10 NGC 2506 OpC 08 00 02.4 -10 46 23   8.28 7.6     ~ 276 0
11 NGC 2682 OpC 08 51 23.0 +11 48 50           ~ 2342 0
12 NGC 3960 OpC 11 50 34.6 -55 40 44   9.07 8.3     ~ 140 0
13 Cl Collinder 261 OpC 12 38 04.6 -68 22 37     10.7     ~ 192 0
14 Cl Trumpler 20 OpC 12 39 31.7 -60 38 13           ~ 112 0
15 NGC 5927 GlC 15 28 00.69 -50 40 22.9           ~ 462 0
16 NGC 6005 OpC 15 55 49.2 -57 26 20   11.90 10.7     ~ 59 0
17 Cl Trumpler 23 OpC 16 00 52.3 -53 32 20     11.2     ~ 51 0
18 NGC 6067 OpC 16 13 11.8 -54 13 37           ~ 211 0
19 NGC 6134 OpC 16 27 48.7 -49 09 40   7.89 7.2     ~ 152 0
20 NGC 6253 OpC 16 59 06.7 -52 42 43     10.2     ~ 186 0
21 NGC 6259 OpC 17 00 46.8 -44 40 41   8.85 8.0     ~ 80 0
22 IC 4651 OpC 17 24 50.9 -49 55 01           ~ 350 0
23 Cl Ruprecht 134 OpC 17 52 44.2 -29 32 13           ~ 41 0
24 NGC 6705 OpC 18 51 03.8 -06 16 19   6.32 5.8     ~ 411 0
25 Cl Berkeley 81 OpC 19 01 40.6 -00 27 14           ~ 82 0
26 NGC 6802 OpC 19 30 36.2 +20 15 43   10.07 8.8     ~ 104 0
27 NAME Galactic Bulge reg ~ ~           ~ 4299 0

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