2016A&A...589A..50D


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.22CEST22:30:00

2016A&A...589A..50D - Astronomy and Astrophysics, volume 589A, 50-50 (2016/5-1)

The extent of mixing in stellar interiors: the open clusters Collinder 261 and Melotte 66.

DRAZDAUSKAS A., TAUTVAISIENE G., RANDICH S., BRAGAGLIA A., MIKOLAITIS S. and JANULIS R.

Abstract (from CDS):

Context. Determining carbon and nitrogen abundances in red giants provides useful diagnostics to test mixing processes in stellar atmospheres.
Aims. Our main aim is to determine carbon-to-nitrogen and carbon isotope ratios for evolved giants in the open clusters Collinder 261 and Melotte 66 and to compare the results with predictions of theoretical models.
Methods. High-resolution spectra were analysed using a differential model atmosphere method. Abundances of carbon were derived using the C2 Swan (0, 1) band head at 5635.5Å. The wavelength interval 7940-8130Å, which contains CN features, was analysed to determine nitrogen abundances and carbon isotope ratios. The oxygen abundances were determined from the [OI] line at 6300Å.
Results. The mean values of the elemental abundances in Collinder 261, as determined from seven stars, are: [C/Fe]=-0.23±0.02 (s.d.), [N/Fe]=0.18±0.09, [O/Fe]=-0.03±0.07. The mean 12C/13C ratio is 11±2, considering four red clump stars and 18 for one star above the clump. The mean C/N ratios are 1.60±0.30 and 1.74, respectively. For the five stars in Melotte 66 we obtained: [C/Fe]=-0.21±0.07 (s.d.), [N/Fe]=0.17±0.07, [O/Fe]=0.16±0.04. The 12C/13C and C/N ratios are 8±2 and 1.67±0.21, respectively.
Conclusions. The 12C/13C and C/N ratios of stars in the investigated open clusters were compared with the ratios predicted by stellar evolution models. The mean values of 12C/13C ratios in Collinder 261 and Melotte 66 agree well with models of thermohaline-induced extra-mixing for the corresponding stellar turn-off masses of about 1.1-1.2M. The mean C/N ratios are not decreased as much as predicted by the model in which the thermohaline- and rotation-induced extra-mixing act together.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: abundances - open clusters and associations: individual: Collinder 261 - stars: horizontal-branch - stars: evolution - open clusters and associations: individual: Melotte 66

Simbad objects: 19

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Number of rows : 19

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 Cl Melotte 66 4118 RB? 07 26 02.5076956557 -47 40 55.930771120     14.6     ~ 11 0
2 Cl Melotte 66 4266 * 07 26 17.2970995921 -47 44 00.058840039     14.55     ~ 12 0
3 Cl Melotte 66 2107 * 07 26 19.8974231894 -47 40 15.854313884   15.627 14.462 14.413 13.52 ~ 14 0
4 Cl Melotte 66 OpC 07 26 23 -47 40.0   8.73 7.8     ~ 175 0
5 Cl* Melotte 66 KJF 1419 RB? 07 26 26.6608887692 -47 37 55.807262138   15.470 14.48   13.29 ~ 13 0
6 Cl Melotte 66 3235 * 07 26 34.5891266149 -47 42 47.163622813   15.780 14.626 14.428 13.39 ~ 14 0
7 NGC 2506 OpC 08 00 01 -10 46.2   8.28 7.6     ~ 228 0
8 NGC 2682 OpC 08 51 18 +11 48.0           ~ 2096 0
9 NGC 3532 OpC 11 05 39 -58 45.2           ~ 277 0
10 Cl* Collinder 261 PJM 2105 * 12 37 34.6667283833 -68 23 25.398023797   14.384 12.937   11.345 ~ 13 0
11 Cl* Collinder 261 PJM 1526 * 12 37 53.95 -68 21 48.8   15.657 14.27   12.85 ~ 9 0
12 Cl* Collinder 261 PJM 1481 * 12 37 55.2242750731 -68 22 36.043992673   15.429 13.95   12.44 ~ 11 0
13 Cl* Collinder 261 SBR 11 * 12 37 59.7124447324 -68 23 49.781954740   15.438 14.145   12.654 ~ 8 0
14 Cl* Collinder 261 PJM 1080 * 12 38 07.2702740490 -68 22 31.009721591   15.387 13.952   12.472 ~ 15 0
15 Cl Collinder 261 OpC 12 38 11.5 -68 22 01     10.7     ~ 163 0
16 Cl* Collinder 261 PJM 906 * 12 38 12.3753086419 -68 20 31.633552817   15.526 14.164   12.72 ~ 12 0
17 Cl* Collinder 261 SBR 5 * 12 38 12.68 -68 21 50.6   15.139 14.139   12.635 ~ 7 0
18 NGC 7789 OpC 23 57 24 +56 42.5   7.68 6.7     ~ 463 0
19 NAME Local Group GrG ~ ~           ~ 7238 0

    Equat.    Gal    SGal    Ecl

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