2009A&A...502..267S


Query : 2009A&A...502..267S

2009A&A...502..267S - Astronomy and Astrophysics, volume 502, 267-282 (2009/7-4)

CNONa and 12C/13C in giant stars of 10 open clusters.

SMILJANIC R., GAUDERON R., NORTH P., BARBUY B., CHARBONNEL C. and MOWLAVI N.

Abstract (from CDS):

Evolved low-mass stars (0.8≤M/M≤2.5) of a wide range of metallicity bear signatures of a non-standard mixing event in their surface abundances of Li, C, and N, and in their 12C/13C ratio. A Na overabundance has also been reported in some giants of open clusters but remains controversial. The cause of the extra-mixing has been attributed to thermohaline convection that should take place after the RGB bump for low-mass stars and on the early-AGB for more massive objects. To track the occurrence of this process over a wide mass range, we derive in a homogeneous way the abundances of C, N, O, and Na, as well as the 12C/13C ratio in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to 3.1M. The sample includes red giants, clump giants, and early-AGB stars. We study the observational behavior of the abundances as well as the possible correlations between different elements and between the chemical abundances and stellar mass. A model atmosphere analysis is conducted using high signal-to-noise ratio, high-resolution FEROS and EMMI spectra. We derive atmospheric parameters using FeI and FeII lines. We calculate abundances for Na, C, N, and O, as well as the 12C/13C ratio using spectral synthesis. For the elements Mg, Ca, Si, Sc, Ti, V, Cr, Co, and Ni, abundances are derived using equivalent widths. A group of first ascent red giants with M/M≤2.5 exhibits lower [N/C] ratios than those measured in clump giants of the same mass range, suggesting an additional increase in the [N/C] ratio after the first dredge-up. The sodium abundances corrected from NLTE are found to be about solar. [Na/Fe] shows a slight increase of 0.10dex as a function of stellar mass in the 1.8 to 3.2M range covered by our sample, in agreement with standard first dredge-up predictions. Our results do not support previous claims of sodium overabundances as high as +0.60 dex. An anti-correlation between 12C/13C and turn-off mass is identified and interpreted as being caused by a post-bump thermohaline mixing. Moreover, we find low 12C/13C ratios in a few intermediate-mass early-AGB stars, confirming that an extra-mixing process also operates in stars that do not experienced the RGB bump. In this case, the extra-mixing possibly acts on the early-AGB, in agreement with theoretical expectations for thermohaline mixing.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: evolution - stars: interiors - stars: atmospheres - open clusters and associations: general

VizieR on-line data: <Available at CDS (J/A+A/502/267): stars.dat tablea1.dat>

Simbad objects: 45

goto Full paper

goto View the references in ADS

Number of rows : 45
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16529 1
2 NGC 2360 62 SB* 07 17 23.9841164232 -15 33 27.078318072 12.81 12.23 11.29     ~ 15 0
3 HIP 35305 * 07 17 35.0707479696 -15 38 35.435230116 12.48 11.80 10.77     ~ 31 0
4 TYC 5965-749-1 * 07 17 43.0357213800 -15 37 32.158140672 12.83 12.10 11.09     ~ 23 0
5 NGC 2360 OpC 07 17 46 -15 37.9           ~ 187 0
6 HIP 35366 * 07 18 19.0082143896 -15 34 59.423559132 12.79 12.10 11.10     ~ 31 0
7 CPD-23 2745 * 07 44 25.7293012440 -23 49 52.987121184   11.05 10.16     ~ 25 0
8 CPD-23 2764 * 07 44 33.6559676712 -23 51 42.125907528   10.46 9.38     ~ 24 0
9 NGC 2447 OpC 07 44 34 -23 51.2           ~ 140 1
10 CD-23 6102 * 07 44 50.2512648336 -23 52 27.129050472   10.78 9.96     ~ 26 0
11 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2234 0
12 HD 95879 * 11 02 50.6037869376 -58 42 07.027505532   8.854 7.869 7.360 6.925 G8III 28 0
13 NGC 3532 OpC 11 05 40 -58 42.4           ~ 320 0
14 CPD-58 3077 * 11 05 45.6255877152 -58 40 39.418236120   9.130 8.189 7.671 7.182 G6III 22 0
15 HD 96445 * 11 05 58.7377615560 -58 43 29.386550208   8.677 7.702 7.200 6.747 G6II-III 29 0
16 CPD-58 3092 * 11 06 03.8390336712 -58 41 15.835743780   8.577 7.457 6.925 6.424 G9III 22 0
17 HD 96789 * 11 07 57.3479444448 -58 17 26.366354556   8.350 6.978 6.374 5.757 K2II 23 0
18 IC 2714 5 * 11 17 21.8771679648 -62 49 45.817741128   12.20 11.10     ~ 14 0
19 IC 2714 OpC 11 17 30 -62 43.1     8.2     ~ 90 0
20 NGC 3680 OpC 11 25 34 -43 14.4   8.40 7.6     ~ 309 0
21 NGC 3680 60 * 11 26 20.7065904912 -43 13 07.467128544   14.99 14.36     ~ 28 0
22 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2257 0
23 CD-53 5815 * 15 02 54.1051176408 -54 12 51.500033784 12.01 10.94 9.72     ~ 16 0
24 CD-53 5829 * 15 03 50.0100652272 -54 14 30.313520772 11.97 11.33 10.26     ~ 25 0
25 HD 132944 * 15 04 02.2509606456 -54 20 21.053959332 11.54 10.36 9.08 8.387   G8/K1(III) 34 0
26 NGC 5822 OpC 15 04 12 -54 22.0           ~ 197 0
27 CD-54 6003 * 15 04 30.3797958024 -54 31 44.812346808 12.11 10.80 9.47     ~ 19 0
28 CD-54 6002 * 15 04 30.5182328328 -54 35 48.846190632   11.51 10.47     ~ 20 0
29 NGC 6134 30 RB? 16 27 45.7194527616 -49 07 33.608498592   13.10 11.93     ~ 15 0
30 NGC 6134 OpC 16 27 49 -49 09.7   7.89 7.2     ~ 145 0
31 NGC 6134 99 RB? 16 27 56.2801997640 -49 10 29.825828580   12.81 11.83     ~ 14 0
32 NGC 6134 202 RB? 16 28 15.7990760592 -49 07 19.483248000   12.86 11.63     ~ 15 0
33 HD 322658 * 17 04 35.9743761504 -37 59 31.050945060   9.27 8.16     K 26 0
34 NGC 6281 OpC 17 04 43 -37 56.9           ~ 126 0
35 HD 322660 * 17 04 47.5386458304 -37 53 14.732713824   9.04 7.94     G 18 0
36 HD 170053 RG* 18 27 14.2812461280 +07 00 32.752668024   8.728 7.301     K0IIb 41 0
37 NGC 6633 OpC 18 27 31.2 +06 34 12           ~ 369 0
38 HD 170174 RG* 18 27 54.7371519576 +06 36 00.341804160   9.39 8.31     G9IIIFe0.5: 66 0
39 BD+05 3805 * 18 35 47.4314134440 +05 20 17.105979624 10.39 10.57 9.54     G8 19 0
40 HD 171658 * 18 35 58.4613268896 +05 24 59.985225180 9.72 10.08 8.86     K5 27 0
41 BD+05 3818 * 18 36 33.2283499464 +05 12 42.780591540 9.83 10.28 9.01     K0 21 0
42 BD+05 3829 * 18 37 05.2144598832 +05 17 31.621063920 10.58 10.93 9.83     G5 35 0
43 BD+05 3850 SB* 18 38 05.1613660152 +05 24 33.720370164 10.02 10.29 9.24     K0 28 0
44 IC 4756 OpC 18 38 31.2 +05 29 24           ~ 226 0
45 NGC 7789 OpC 23 57 20 +56 43.6   7.68 6.7     ~ 497 0

To bookmark this query, right click on this link: simbad:objects in 2009A&A...502..267S and select 'bookmark this link' or equivalent in the popup menu


2023.02.07-16:50:13

© Université de Strasbourg/CNRS

    • Contact